Power conversion apparatus

ABSTRACT

Technology leading to a size reduction in a power conversion apparatus comprising a cooling function and technology relating to enhancing productivity and enhancing reliability necessary for commercial production are provided. Series circuits comprising an upper arm and lower arm of an inverter circuit are built in a single semiconductor module  500.  The semiconductor module has cooling metal on two sides. An upper arm semiconductor chip and lower arm semiconductor chip are wedged between the cooling metals. The semiconductor module is inserted inside a channel case main unit  214.  A DC positive electrode terminal  532,  a DC negative electrode terminal  572,  and an alternating current terminal  582  of a semiconductor chip are disposed in the semiconductor module. The DC terminals  532  and  572  are electrically connected with a terminal of a capacitor module. The alternating current terminal  582  is electrically connected with a motor generator via an AC connector.

This application is a continuation application of U.S. application Ser.No. 12/019,990, filed on Jan. 25, 2008, now allowed, the entirety ofwhich is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a power conversion apparatus comprisingan inverter circuit.

2. Background Art

As conventional technology that is designed to improve heat dissipationproperties by efficiently conducting heat from a semiconductor module toa cooler, for example, a cooling structure disclosed in JP PatentPublication (Kokai) No. 2005-175163A has been proposed. According to JPPatent Publication (Kokai) No. 2005-175163A, a semiconductor module isinserted into a hole for module insertion that is formed at a cooler todissipate heat from an abutting surface of the hole for moduleinsertion. The surface that abuts with the hole for module insertion ofthe semiconductor module is coated with a soft metal layer to dissipateheat to the cooler through the soft metal layer.

Further, as conventional technology designed to achieve compatibilitybetween assemblability and cooling efficiency of a semiconductor deviceused in an inverter, for example, the inverter device described in JPPatent Publication (Kokai) No. 2005-237141A has been proposed. Accordingto JP Patent Publication (Kokai) No. 2005-237141A, a structure isdisclosed in which are formed accommodating portions that accommodatepower cards on which both sides of semiconductor devices are sandwichedby heat radiating plates and recycling path portions that recyclecoolant around the power cards. In this structure, gaps between thepower cards and the accommodating portions are filled with an insulatingresin, and the insulating resin is cured to fix the power cards.

Furthermore, an example of the conventional technology for a coolingstructure designed to reduce the burden of assembling a semiconductormodule and enhance cooling performance is proposed in JP PatentPublication (Kokai) No. 2006-202899A. According to JP Patent Publication(Kokai) No. 2006-202899A, a block is provided that accommodates asemiconductor module therein and that has heat radiating surfaces thatrelease Joule heat that is generated in the semiconductor at a frontsurface and a rear surface. By inserting the block into a cooling waterpassage that is formed inside a case, the front surface and the rearsurface of the block face the cooling water passage.

SUMMARY OF THE INVENTION

In recent years, for example with respect to automobiles, electricmotorization of respective on-vehicle systems of vehicles, beginningwith the vehicle drive system, has been progressing. However, forelectric motorization of an on-vehicle system it is necessary to newlyadd electrical equipment that drives a member to be driven and a powerconversion apparatus that controls the driving of a dynamo-electricmachine by controlling power that is supplied to the dynamo-electricmachine from an on-vehicle electrical supply. It is also necessary toreplace component parts of the conventional system.

A power conversion apparatus has, for example in a vehicle, a functionof converting direct-current power that is supplied from an on-vehicleelectrical supply into alternating current power for driving adynamo-electric machine, or converting alternating current powergenerated by a dynamo-electric machine into direct-current power forsupply to an on-vehicle electrical supply. Although the amounts ofelectric power to be converted by power conversion apparatuses aretending to increase, since there is a tendency towards making vehiclesmore compact and lightweight overall, increases in the size and weightof power conversion apparatuses are being suppressed. Further, incomparison to power conversion apparatuses for industrial use, powerconversion apparatuses for vehicle use are required to be used inenvironment with large temperature variations. Power conversionapparatuses for vehicles are thus required that can convert a relativelylarge amount of power with a comparatively small size and that canmaintain high reliability while installed in a high temperatureenvironment.

A power conversion apparatus comprises an inverter circuit. Powerconversion between direct-current power and alternating current power isperformed by operation of the inverter circuit. To perform this powerconversion it is necessary for a power semiconductor that constitutesthe inverter circuit to repeat switching operations (changeoveroperations) between a cutoff state and a conducting state. A largeamount of heat is generated at the power semiconductor when performingthe changeover operations. The temperature of a semiconductor chip thatis a power semiconductor of the inverter circuit increases due to theheat the semiconductor chip generates at the time of a switchingoperation. Therefore, suppressing this temperature increase is animportant issue.

Since the amount of generated heat of a semiconductor chip increaseswhen the power to be converted increases, as a countermeasure it isnecessary to increase the semiconductor chip size or the number ofsemiconductor chips used, and as a result the size of the powerconversion apparatus increases. A configuration in which the coolingefficiency of a semiconductor chip is enhanced may be considered as onemethod that suppresses this kind of increase in size of the powerconversion apparatus. For example, JP Patent Publication (Kokai) Nos.2005-175163A, 2005-237141A, and 2006-202899A have been proposed asmethods to enhance the cooling efficiency of semiconductor chips.

Although it is clear that enhancing the cooling efficiency ofsemiconductor chips leads to a increased compactness of thesemiconductor chips, it is difficult to say that this always leads tosuppression of an increase in the size of the overall power conversionapparatus. For example, it can be considered that when an improvement ismade to increase the cooling efficiency of semiconductor chips, theoverall configuration of the power conversion apparatus becomescomplicated as a result, and cases may arise in which although the sizeof the semiconductor chips can be reduced, it is not really possible toreduce the size of the overall power conversion apparatus.

Accordingly, in order to suppress an increase in the size of the overallpower conversion apparatus, it is necessary to enhance the coolingefficiency of the semiconductor chips in a manner that takes the overallpower conversion apparatus into consideration, and it is necessary tosuppress as much as possible electrical or mechanical complexities inthe overall power conversion apparatus. It is hard to say that theinventions disclosed in the above described JP Patent Publication(Kokai) Nos. 2005-175163A, 2005-237141 A, and 2006-202899A give adequateconsideration to reducing the size of the overall power conversionapparatus.

An object of the present invention is to provide technology that leadsto a reduction in the size of power conversion apparatuses. Further, apower conversion apparatus according to an embodiment of the presentinvention as described hereunder includes improvements relating not onlyto size-reduction technology but also to enhancing the reliabilityrequired for commercial production and enhancing productivity.

One of the fundamental features of the present invention for solving theforegoing problems is that a series circuit comprising an upper arm anda lower arm of an inverter circuit is built inside a singlesemiconductor module, the semiconductor module has a cooling metal onboth sides, an upper arm semiconductor chip and a lower armsemiconductor chip for constituting the series circuit having the upperarm and the lower arm are inserted between the cooling metals, and thesemiconductor module is inserted into a cooling channel.

The power conversion apparatus according to the embodiment of thepresent invention as described hereunder solves many of the problemsrequired for commercial production. These problems and means for solvingthe problems are described in detail hereunder, and examples of meansfor solving the problems chiefly include the following configurationexamples:

A power conversion apparatus, having:

a channel case having a cooling channel built therein, a two-sidedcooling semiconductor module having built therein an upper and lower armseries circuit of an inverter circuit, a capacitor module, adirect-current (DC) connector, and an alternative-current (AC)connector, wherein:

the two-sided cooling semiconductor module has a first and a second heatradiating metal in which an outside surface is a heat radiating surface,the upper and lower arm series circuit being hermetically disposedbetween the first and second heat radiating metals, and having adirect-current (DC) positive electrode terminal, a direct-current (DC)negative electrode terminal, and an alternating current terminal thatprotrude externally;

an opening is provided in the channel case, and a plurality of thetwo-sided cooling semiconductor modules are disposed such that first anda second heat radiating metals of the two-sided cooling semiconductormodules are inserted inside the cooling channel from the opening;

insulating members are respectively disposed on an inside surface sideof the first and second heat radiating metals of the two-sided coolingsemiconductor module, and a plurality of semiconductor chips forconstituting an upper and lower arm series circuit are disposed betweenthe insulating members;

on the inside of the two-sided cooling semiconductor module arerespectively disposed a direct-current (DC) positive electrodeconductor, a direct-current (DC) negative electrode conductor, and analternating current conductor that electrically connect, respectively,the plurality of semiconductor chips and the DC positive electrodeterminal, the DC negative electrode terminal, and the alternatingcurrent terminal; and

the DC positive electrode terminal and the DC negative electrodeterminal of the two-sided cooling semiconductor module are respectivelyelectrically connected to a terminal of the capacitor module andelectrically connected to the DC connector, and the alternating currentterminals of the plurality of two-sided cooling semiconductor modulesare respectively electrically connected to the AC connector.

Further, a power conversion apparatus, having:

a channel case having a cooling channel built therein, a two-sidedcooling semiconductor module having built therein an upper and lower armseries circuit of an inverter circuit, and a capacitor module, wherein:

the two-sided cooling semiconductor module has a first and a second heatradiating metal having heat radiating fins on one surface, the upper andlower arm series circuit being hermetically disposed between the firstand second heat radiating metals, and has a DC positive electrodeterminal, a DC negative electrode terminal, and an alternating currentterminal that protrude externally;

in the two-sided cooling semiconductor module, the first and second heatradiating metals are opposingly disposed such that heat radiatingsurfaces face outward relative to each other at an interval that isshorter than a length along a cooling channel of the heat radiatingmetals, the DC positive electrode terminal, the DC negative electrodeterminal, and the alternating current terminal protrude from a side thatis sandwiched between the first and second heat radiating metals, andthe DC positive electrode terminal and the DC negative electrodeterminal are opposingly disposed;

a plurality of openings are provided in the channel case, and aplurality of the two-sided cooling semiconductor modules are disposedsuch that the heat radiating metals of the two-sided coolingsemiconductor modules are respectively inserted inside the coolingchannel from the plurality of openings;

in the two-sided cooling semiconductor module, insulating members arerespectively disposed on another surface of the opposing first andsecond heat radiating metals, a plurality of semiconductor chips forconstituting the upper and lower arm series circuit are disposed on theinside of the insulating members, and a semiconductor chip acting as theupper arm and a semiconductor chip acting as the lower arm are disposedin a staggered fashion with respect to each other in an insertiondirection from the opening of the two-sided cooling semiconductormodule;

on the inside of the two-sided cooling semiconductor module are furtherdisposed a DC positive electrode conductor, a DC negative electrodeconductor, and an alternating current conductor that electricallyconnect, respectively, the upper and lower arm series circuit and the DCpositive electrode terminal, the DC negative electrode terminal, and thealternating current terminal; and

the DC positive electrode terminal and the DC negative electrodeterminal of the two-sided cooling semiconductor module are respectivelyelectrical connect with a terminal of the capacitor module.

Further, a power conversion apparatus, having:

a channel case having a cooling channel built therein, a two-sidedcooling semiconductor module having built therein an upper and lower armseries circuit of an inverter circuit, and a capacitor module, wherein:

the two-sided cooling semiconductor module has a first and a second heatradiating metal having heat radiating fins on one surface, hasrespective insulating members on another surface of the first and secondheat radiating metals, the upper and lower arm series circuit beingdisposed between the respective insulating members, and has a DCpositive electrode terminal, a DC negative electrode terminal, analternating current terminal, and a signal terminal that protrudeexternally;

in the two-sided cooling semiconductor module, the first and second heatradiating metals are disposed such that the respective insulatingmembers face each other at an interval that is shorter than a lengthalong a cooling channel of the heat radiating metals, the DC positiveelectrode terminal, the DC negative electrode terminal, the alternatingcurrent terminal, and the signal terminal protrude from a side that isperpendicular with a plane of the respective insulating members, and theDC positive electrode terminal and the DC negative electrode terminalare opposingly disposed;

a plurality of openings are provided in the channel case, and thetwo-sided cooling semiconductor modules are respectively inserted insidethe cooling channel from the plurality of openings such that a pluralityof the two-sided cooling semiconductor module are retained in thechannel case;

a plurality of semiconductor chips for constituting an upper and lowerarm series circuit are disposed between the insulating members that arerespectively provided on the other surface of the first and second heatradiating metals of the two-sided cooling semiconductor module;

a heat conduction path is formed through the insulating members betweensurfaces of the semiconductor chip acting as the upper arm and thesemiconductor chip acting as the lower arm of the upper and lower armsand respectively opposing other surfaces of the first and second heatradiating metals;

inside the two-sided cooling semiconductor module are further disposed aDC positive electrode conductor, a DC negative electrode conductor, analternating current conductor, and a signal conductor that electricallyconnect the plurality of semiconductor chips acting as the upper andlower arms and the DC positive electrode terminal, the DC negativeelectrode terminal, the alternating current terminal, and the signalterminal, respectively; and

the DC positive electrode terminal and the DC negative electrodeterminal of the two-sided cooling semiconductor module are respectivelyelectrically connected with a terminal of the capacitor module.

Further, a power conversion apparatus, having:

a channel case having built therein a cooling channel having a pluralityof insertion openings, a semiconductor module having built therein anupper and lower arm series circuit of an inverter circuit and which isinserted into the cooling channel from the insertion opening, and acapacitor module; wherein:

the plurality of insertion openings are formed in a parallelly disposedcondition in the cooling channel;

a plurality of the semiconductor modules are parallelly disposed andretained in the channel case such that each of the semiconductor modulesis inserted into the cooling channel from the parallelly disposedinsertion openings;

the semiconductor module has a first and a second heat radiating metalhaving a heat radiating surface provided at one surface and aninsulating member provided at another surface in a state in which therespective heat radiating surfaces are parallelly disposed so as to faceoutward with respect to each other, has an upper arm semiconductor chipand a lower arm semiconductor chip that constitute the upper and lowerarm series circuit in a hermetically sealed state between the respectiveinsulating members that are provided in the first and second heatradiating metals and, further, has a control terminal for controllingthe lower arm semiconductor chip, a control terminal for controlling theupper arm semiconductor chip, an alternating current terminal, a DCnegative electrode terminal, and a DC positive electrode terminal thatprotrude externally;

in the insulating member of the first heat radiating metal are provideda first conductor for serial connection and a positive electrode sideconductor electrically connecting to the DC positive electrode terminal,in the insulating member of the second heat radiating metal are provideda second conductor for serial connection and a negative electrode sideconductor electrically connecting to the DC negative electrode terminal,the positive electrode side conductor and the second conductor beingopposingly disposed, and the negative electrode side conductor and thefirst conductor being opposingly disposed; and

one of the semiconductor chips for the upper and lower arms is disposedbetween the positive electrode side conductor and the second conductor,and an other of the semiconductor chips for the upper and lower arms isdisposed between the negative electrode side conductor and the firstconductor, with the first conductor, the second conductor, and thealternating current terminal being electrically connected.

Further, a power conversion apparatus, having:

a channel case having cooling channels that are looped back a pluralityof times and formed in parallel; and

a plurality of semiconductor modules having an upper and lower armseries circuit of an inverter circuit built therein, a DC positiveelectrode terminal, a DC negative electrode terminal, and an alternatingcurrent terminal, and a capacitor module having a capacitor builttherein; wherein:

in the channel case, a plurality of openings that respectivelycommunicate with the parallelly formed cooling channels are formed in aparallel positional relationship, the semiconductor modules arerespectively inserted into the plurality of openings, the plurality ofsemiconductor modules are fixed in a parallelly disposed positionalrelationship, and the capacitor module is fixed in the channel case in adisposition relationship in which the capacitor module is disposed alongan axis of parallel disposition of the semiconductor modules; and

the DC positive electrode terminal, the DC negative electrode terminal,and the alternating current terminal of the semiconductor module aredisposed such that the DC positive electrode terminal and the DCnegative electrode terminal of the semiconductor module are disposedbetween the capacitor module and the alternating current terminal of aplurality of the semiconductor modules that are parallelly disposed, andthe DC positive electrode terminal and the DC negative electrodeterminal of the semiconductor module are electrically connected,respectively, with a terminal of the capacitor module.

According to the present invention, the cooling efficiency of asemiconductor chip constituting an inverter circuit can be enhanced.This enhancement of cooling capability leads not merely to a reductionin the size of the semiconductor module, but also to a reduction in thesize of the overall inverter device.

In addition to a reduction in size that is the above described effect ofthe present invention, the power conversion apparatus according to theembodiment of the present invention also achieves effects that overcomemany problems as required for commercial production. The solution ofthese many problems and effects produced by solving the problems aredescribed in detail in combination with the description of theembodiment in the section that provides a detailed description of thepreferred embodiment below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view illustrating a control block of a hybrid vehicle;

FIG. 2 is a view illustrating the circuit configuration of a vehicledrive electrical equipment system that includes a power conversionapparatus comprising an inverter device including an upper and lower armseries circuit and a control portion, and a capacitor that is connectedto a direct current side of the inverter device, as well as a batteryand a motor generator;

FIG. 3 is a view illustrating the circuit configuration of a powerconversion apparatus in which two upper and lower arm series circuitsare employed for outputting alternating current of respective phases toa motor generator;

FIG. 4 is a view that illustrates the external shape of a powerconversion apparatus according to an embodiment of the presentinvention;

FIG. 5 is an exploded view that gives a perspective view of the internalstructure of a power conversion apparatus according to the presentembodiment;

FIG. 6 is an oblique perspective view of a state in which an upper caseis removed from the power conversion apparatus according to the presentembodiment;

FIG. 7 is an oblique perspective view of a state in which an upper case,a capacitor, and a bus bar assembly are removed from the powerconversion apparatus according to the present embodiment;

FIG. 8 is an oblique perspective view showing a configuration example oftwo inverter devices in the power conversion apparatus according to thepresent embodiment, which shows a state in which a bus bar assembly andan upper case are removed;

FIG. 9 is an oblique perspective view showing a configuration example oftwo inverter devices in the power conversion apparatus according to thepresent embodiment, which shows a state in which a bus bar assembly, anupper case, and a capacitor module are removed;

FIG. 10 is a plan view showing a configuration example of two inverterdevices in the power conversion apparatus according to the presentembodiment, which shows a state in which a bus bar assembly, an uppercase, and a capacitor module are removed;

FIG. 11 is a sectional view that illustrates the flow of cooling waterin a channel case in which semiconductor modules are loaded that relatesto the present embodiment;

FIG. 12 is a sectional view showing the flow of cooling water in achannel case in which semiconductor modules are loaded for the twoinverter devices shown in FIG. 9;

FIG. 13 is a plan view that shows the disposition situation in a channelcase of a positive electrode terminal, a negative electrode terminal, analternating current terminal, a signal terminal, and a gate terminal ofsemiconductor modules that are parallelly connected for each phase to amotor shown in FIG. 3;

FIG. 14 is an oblique perspective view that illustrates a channel casemain unit in which semiconductor modules are loaded, a channel casefront surface portion, and a channel case rear surface portion;

FIG. 15 is a sectional view that illustrates a channel case main unit inwhich semiconductor modules are loaded, a channel case front surfaceportion, and a channel case rear surface portion;

FIG. 16 is an oblique perspective view that illustrates a state in whichsemiconductor modules are being loaded in a channel case main unit;

FIG. 17 is a front view that illustrates a state in which semiconductormodules are being loaded in a channel case main unit;

FIG. 18 is a view that shows the external appearance of a semiconductormodule with heat radiating fins and a built-in upper and lower armseries circuit in a power conversion apparatus according to the presentembodiment;

FIG. 19 is a sectional view of the semiconductor module shown in FIG.18;

FIG. 20 is an expansion plan of a semiconductor module including a case;

FIG. 21 is a sectional view of the semiconductor module shown in FIG.20;

FIG. 22 is a view that shows an oblique perspective of the internalstructure of a semiconductor module relating to the present embodimentthat shows heat radiating fins (A side) on one side of the semiconductormodule and heat radiating fins (B side) on the other side thereof;

FIG. 23 is a view that illustrates the structure of an upper and lowerarm series circuit that is adhered to the inside of heat radiating fins(A side) of a semiconductor module;

FIG. 24 is an oblique perspective view that illustrates the structure ofan upper and lower arm series circuit that is adhered to the inside ofheat radiating fins (B side) of a semiconductor module;

FIG. 25 is an oblique perspective view that illustrates the structure ofan upper and lower arm series circuit that is adhered to the inside ofheat radiating fins (A side) of a semiconductor module;

FIG. 26 is a front view of the structure shown in FIG. 25;

FIG. 27 is an oblique perspective view that shows a wire bonding stateand a structure of a conductor plate that is bonded by a vacuumthermocompression method to the inside of heat radiating fins of asemiconductor module;

FIG. 28 is an explanatory view of vacuum thermocompression bonding of aconductor plate via a heat radiating sheet to heat radiating fins of asemiconductor module;

FIG. 29 is a view that represents the flow of cooling water of heatradiating fins (A side) in a semiconductor module related to the presentembodiment;

FIG. 30 is a view that represents the relation between cooling waterflow in a semiconductor module and the layout of a circuitconfiguration;

FIG. 31 is a view showing connection terminals of a capacitor module ofthe power conversion apparatus according to the present embodiment;

FIG. 32 is an oblique perspective view illustrating a connection statebetween a capacitor module and a semiconductor module relating to thepresent embodiment;

FIG. 33 is a sectional view illustrating a connection state between acapacitor module and a semiconductor module relating to the presentembodiment;

FIG. 34 is a structural layout drawing that illustrates an inductancelowering effect of a semiconductor module relating to the presentembodiment;

FIG. 35 is a circuit layout drawing that illustrates an inductancelowering effect of a semiconductor module relating to the presentembodiment;

FIG. 36 is an oblique perspective view that shows another configurationexample of a semiconductor module relating to the present embodiment;

FIG. 37 is a sectional view that shows another configuration example ofa semiconductor module relating to the present embodiment, which is aview as seen from the dotted-line arrows shown in FIG. 36;

FIG. 38 is an oblique perspective view that illustrates the flow ofcooling water in another configuration example of the semiconductormodule relating to the present embodiment;

FIG. 39 is a sectional view that illustrates the flow of cooling waterin a case in which another configuration example of the semiconductormodule relating to the present embodiment is loaded in a water-cooledcase;

FIG. 40 is another sectional view showing the flow of cooling water oftwo upper and lower tiers in a case in which another configurationexample of the semiconductor module relating to the present embodimentis loaded in a water-cooled case;

FIG. 41 is a view showing a configuration example that enlarges the areaof an emitter electrode of an IGBT chip in a semiconductor module; and

FIG. 42 is a view that shows a configuration in which a control boardhaving a control circuit shown in FIG. 5 is disposed at the bottom of achannel case.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The power conversion apparatus according to the embodiment of thepresent invention is described below in detail while referring to thedrawings. However, first, an overview of technical problems to beovercome and improved in regard to the power conversion apparatusaccording to the embodiment and technology for solving the technicalproblems are described.

The power conversion apparatus according to the embodiment of thepresent invention has been made in consideration of the followingtechnical aspects as a product that can respond to the needs of themarketplace. One of those aspects is size-reduction technology, that is,technology that inhibits as much as possible an increase in size of apower conversion apparatus accompanying an increase in the amount ofpower that is converted. Another aspect is technology that relates toimproving the reliability of a power conversion apparatus. A furtheraspect is technology that relates to improving the productivity of apower conversion apparatus. The power conversion apparatus according tothe embodiment of the present invention has been achieved based on theaforementioned three aspects as well as on an aspect that combines thesethree aspects. The features of the power conversion apparatus accordingto each of these aspects are reviewed hereunder.

(1) Description Relating to Size-Reduction Technology

The power conversion apparatus according to the present embodiment has astructure in which an upper and lower arm series circuit of an inverteris housed inside a semiconductor module that comprises a cooling metalon both sides, the semiconductor module is inserted inside coolingwater, and the cooling metal on both sides is cooled by the coolingwater. By adopting this structure, the cooling efficiency is improvedand a reduction in the size of the semiconductor module is enabled. As aspecific example, respective insulating sheets or insulating plates suchas ceramic plates are provided as insulating members on the inside ofthe cooling metal on both sides, and a semiconductor chip of an upperarm and a lower arm constituting an upper and lower arm series circuitis inserted between conductor metals that are fixed to the respectiveinsulating members. With this structure, favorable heat conduction pathscan be made between the two sides of the semiconductor chips of theupper arm and lower arm and the cooling metals, thereby significantlyimproving the cooling efficiency of the semiconductor module.

Further, in the semiconductor module, since the semiconductor chips ofthe lower arm and the upper arm are disposed in a condition in whichthey are staggered in the vertical direction with respect to the axis ofthe flow of cooling water, the cooling water inside the cooling channelcan be utilized more efficiently, thereby enhancing the cooling effect.

By adopting a structure in which, in addition to disposing asemiconductor chip of the upper arm of the semiconductor module and asemiconductor chip of the lower arm of a semiconductor module in astaggered condition in the vertical direction with respect to the axisof the flow of cooling water, a channel at a position corresponding to asemiconductor chip of an upper arm and a channel at a positioncorresponding to a semiconductor chip of a lower arm are divided andthese channels are connected in series, it is possible to narrow thesectional area of the channel to suit the semiconductor chips that arethe cooling objects, and as a result the flow rate of cooling waterwithin the channels can be increased. An increase in the flow rateresults in an increase in the amount of water contributing to coolingper unit of time. This leads to a significant improvement in coolingefficiency. This structure that divides a channel at a positioncorresponding to a semiconductor chip of an upper arm or a lower armdoes not make the overall cooling structure particularly complex, andhas an effect that the cooling efficiency can be significantly enhancedwithout causing a major increase in the size of the cooling case.

The two surfaces of the semiconductor chips of the upper arm and thelower arm are respectively connected to a conductor metal (conductorplate) on the inside of a cooling metal. The conductor metals are fixedvia insulating members to the cooling metals. The insulating members areformed to have a thin thickness, for example, not more than 350 μ-metersin the case of a ceramic plate, and in the case of an insulating sheetthe thickness is even less at a level from 50 μ-meters to 200 μ-meters.In this case, for example, a sheet of resin that is bonded bythermocompression is employed as an insulating sheet. Since a conductormetal is disposed in the vicinity of a cooling metal, an eddy currentcaused by an electric current flowing in the conductor metal flows tothe cooling metal, and although the eddy current generates heat, thisheat is effectively transferred to the cooling water.

Further, inductance within the semiconductor module is lowered by theeddy current. Lowering the inductance makes it possible to reduce a jumpin voltage caused by a switching operation with respect to thesemiconductor chips of the upper arm and lower arm, and thus leads to anincrease in reliability. Further, suppressing a voltage increase makesit possible to speed up a switching operation for semiconductor chips ofthe upper arm and lower arm. As a result, the time required for theswitching operation can be reduced, leading to a reduction in the amountof heat generated by the switching operation.

According to power conversion apparatus of the present embodiment, sincean upper and lower arm series circuit of an inverter is housed inside asemiconductor module, the structure is one in which a direct current(DC) terminal of a semiconductor module connects to a capacitor module,and furthermore the terminal structure of the capacitor module is anextremely simple structure. This contributes significantly to decreasingthe size of the inverter device overall, and at the same time leads toimprovements in reliability and improvements in productivity.

Further, it is possible to make a structure of a terminal of a capacitormodule or a DC terminal of a semiconductor module as well as a structureconnecting these into a structure in which terminals on a positiveelectrode side and a negative electrode side as well as a conductorconnecting to these terminals are close to each other and a structure inwhich they are opposingly disposed, and the inductance between asemiconductor module and a capacitor can be reduced. It is therebypossible to decrease a voltage jump caused by a switching operation forsemiconductor chips of an upper and lower arm, leading to an improvementin reliability. Further, suppression of a voltage rise makes it possibleto speed up a switching operation for semiconductor chips, leading to areduction in the amount of heat generated as a result of the decrease inthe switching operation time. Reducing the amount of generated heat orinhibiting complication of the connection structure makes it possible toreduce the size of the power conversion apparatus.

Further, according to the power conversion apparatus of the presentembodiment, since the cooling efficiency can be significantly improved,engine cooling water can be used as cooling water. In the case ofcooling with cooling water that is different to engine cooling water,the vehicle requires a new cooling system, and even if it is possible todecrease the size of the power conversion apparatus, the system of theoverall vehicle is complicated. According to the present embodiment,even supposing that the size of the power conversion apparatus were toincrease, utilization of engine cooling water enables size reductionswith respect to the overall vehicle and also has many other advantages.

According to the power conversion apparatus of the present embodiment,since a configuration is adopted in which a semiconductor module or acapacitor module is fixed in a cooling case, a surface of the coolingcase comprising the semiconductor module can be utilized as a surfacethat fixes a capacitor module, and it is thus possible to reduce thesize of the power conversion apparatus. Further, since the coolingefficiency of the capacitor module is enhanced and the capacitor modulecan be fixingly retained by the cooling case, the structure is alsostrengthened with respect to vibrations and has the effects of sizereduction and reliability enhancement.

(2) Description Relating to Reliability Enhancement

According to the power conversion apparatus of the present embodiment,as described above, the cooling efficiency of a semiconductor module canbe significantly improved and, as a result it is possible to inhibitincreases in temperature of the semiconductor chips, leading to animprovement in reliability.

Further, it is possible to achieve low inductance in the semiconductormodule or low inductance between the semiconductor module and thecapacitor module and to reduce a voltage jump caused by switchingoperations, and this leads to an improvement in reliability. Further,suppression of a voltage rise makes it possible to speed up a switchingoperation for semiconductor chips, leading to a reduction in the amountof heat generated as a result of the decrease in the switching operationtime. This also leads to inhibition of a temperature increase andenhancement of reliability.

The structure connecting the DC terminal of the semiconductor module toa capacitor module and, furthermore, the terminal structure of thecapacitor module are simple structures, and this leads not only toincreased productivity and size reduction, but also to enhancement ofreliability.

According to the present power conversion apparatus, since the coolingefficiency is significantly improved, engine cooling water can be usedas cooling water. Therefore, a dedicated cooling water system is notrequired in the case of a vehicle, and the reliability of the vehicleoverall can be significantly improved.

According to the present power conversion apparatus a structure isadopted in which a semiconductor module that houses an upper and lowerarm series circuit of an inverter is inserted into a cooling channelfrom an opening provided in the channel. It is possible to perform aprocess in which a semiconductor module and a channel case that areseparately produced on a production line are inspected separately, andthereafter a step is performed in which the semiconductor module isfixed in the channel case. Since it is possible to separately produceand inspect a semiconductor module that is an electrical component and achannel case that is a mechanical component in this manner, whilenaturally the productivity is enhanced, this also leads to animprovement in reliability.

Further, for the semiconductor module, a method can be adopted in whichthe semiconductor module is produced by fixing necessary conductors orsemiconductor chips to a first and second heat radiating metal,respectively, and thereafter integrating the first and second heatradiating metals. Since it is possible to perform a step of integratingthe heat radiating metals after verifying the production state of thefirst and second heat radiating metals, respectively, this leads to notjust improved productivity but also to enhanced reliability. Further,since the structure is one in which a DC terminal or alternating currentterminal or a signal terminal (signal emitter terminal) or gate terminalof the semiconductor module is fixed to either the first or second heatradiating metal within a semiconductor module, the structure has astrong resistance to vibrations and reliability is thereby improved.

According to the present power conversion apparatus, the structure isone in which when a collector surface of a semiconductor chip of theupper arm is fixed to a first heat radiating metal the collector surfaceof a semiconductor chip of a lower arm is fixed to the same first heatradiating metal, and the collector surface and the emitter surface ofsemiconductor chips of the upper and lower arms are disposed in the samedirection. By adopting this structure reliability is improved along withan improvement in productivity.

The structure is also one in which semiconductor chips of the upper andlower arms and a signal terminal or a gate terminal of the upper andlower arms are fixed by the same heat radiating metal. It is thereforepossible to bring together wire bonding connection steps that joinsemiconductor chips with a signal terminal or a gate terminal on one ofthe heat radiating metals, which facilitates inspection and the like.This leads to not only improved productivity, but also enhancedreliability.

(3) Description Relating to Productivity Enhancement

According to the power conversion apparatus of the present embodiment,as described above, it is possible to separately produce a semiconductormodule and a cooling case and thereafter perform a step of fixing thesemiconductor module in the cooling case, thereby enabling production ofa semiconductor module with an electrical production line. Productivityand reliability are thereby improved. Further, since a capacitor modulecan also be similarly produced in another production step and thereafterfixed in the channel case, productivity improves.

It is also possible to fix semiconductor modules and a capacitor modulein the channel case and thereafter connect terminals of thesemiconductor modules and the capacitor module, and to secure a spacefor introducing a welding machine for connecting into a welding portion,and this leads to enhanced productivity. Further, in these connectionsteps, since terminals of the semiconductor module are fixed torespective heat radiating metals of the semiconductor module, heatproduced when welding a terminal is diffused to the respective heatradiating metals, enabling the suppression of adverse effect on thesemiconductor chips and ultimately leading to improvement inproductivity and improvement in reliability.

Further, since semiconductor chips of the upper and lower arms and asignal terminal or a gate terminal of the upper and lower arms can befixed to one of the heat radiating metals of a semiconductor module,wire bonding can be performed for both the upper arm and lower arm withone of the heat radiating metal production lines, and thus productivityimproves.

According to the power conversion apparatus of the present embodiment,it is possible to mass produce semiconductor modules of the samestructure, adopt a system in which the number of semiconductor modulesrequired on the basis of the requirement specifications of the powerconversion apparatus are used, to carry out planned semiconductor modulemass production, and improve productivity while at the same time withlowering prices and enhancing reliability. This completes thedescription of the structural effects and features of the powerconversion apparatus according to the embodiment of the presentinvention as seen from three technical aspects.

Next, the power conversion apparatus according to the embodiment of thepresent invention is described in detail while referring to thedrawings. Although the power conversion apparatus according to theembodiment of the present invention can be applied to a hybrid vehicleor a purely electric vehicle, as a representative example, a circuitconfiguration of the power conversion apparatus and a control structurein a case in which the power conversion apparatus according to theembodiment of the present invention is applied to a hybrid vehicle aredescribed using FIG. 1 and FIG. 2. FIG. 1 is a view that shows a controlblock of a hybrid vehicle. FIG. 2 is a view that illustrates the circuitconfiguration of a vehicle drive electrical equipment system thatincludes a power conversion apparatus comprising an inverter deviceincluding an upper and lower arm series circuit and a control portion,and a capacitor that is connected to a direct current side of theinverter device, as well as a battery and a motor generator.

For the power conversion apparatus according to the embodiment of thepresent invention, a description is made in which a power conversionapparatus for vehicle mounting of an on-vehicle electrical equipmentsystem to be mounted in a vehicle, in particular, a vehicle driveelectrical equipment system is used, taking an example of an inverterdevice for vehicle drive for which a mounting environment and anoperational environment are extremely severe. The inverter device forvehicle drive comprises a vehicle drive electrical equipment system as acontrol device that controls the driving of a vehicle drive motor,converts direct-current power that is supplied from an on-vehicle powergenerating device or an on-vehicle battery constituting an on-vehicleelectrical supply into a predetermined alternating current power, andsupplies the obtained alternating current power to the vehicle drivemotor to control driving of the vehicle drive motor. Further, since thevehicle drive motor also has a function as a power generator, theinverter device for vehicle drive also has a function that, inaccordance with the operation mode, converts alternating current powergenerated by the vehicle drive motor into direct-current power. Thethus-converted direct-current power is supplied to the on-vehiclebattery.

In this connection, although the configuration of the present embodimentcan also be applied to an inverter device other than that for vehicledrive, for example, to an inverter device used as a control device of anelectric powered brake device or an electric power steering device, themost desirable effect is exerted when the configuration of the presentembodiment is applied for vehicle drive use. Further although theconcept of the present embodiment can also be applied to other powerconversion apparatuses for vehicle mounting such as a directcurrent-direct current power conversion apparatus, such as a DC/DCconverter or a DC chopper, or an alternating current-direct currentpower conversion apparatus, the most desirable effect is exerted whenthe present embodiment is applied for vehicle drive use. Furthermore,although the present embodiment can also be applied to an industrialpower conversion apparatus that is used as a control device of anelectric motor that drives equipment of a factory or to a domestic powerconversion apparatus used for a control device of an electric motor thatdrives a domestic solar power generation system or domestic electricalappliances, as described above the most desirable effect is exerted whenthe present embodiment is applied for vehicle drive use.

A case will now be described in which it is assumed that a vehicle driveelectrical equipment system comprising an inverter device for vehicledrive to which the present embodiment is applied is mounted in a hybridvehicle that is configured to drive either the front or rear wheels byemploying as a driving source an engine that is an internal combustionengine and a vehicle drive motor. In some hybrid vehicles either thefront or rear wheels are driven by an engine and the other wheels aredriven by a vehicle drive motor, and the present embodiment can beapplied to any type of hybrid vehicle. Furthermore, as described above,the present embodiment can also be applied to a purely electric vehiclesuch as a fuel cell electric vehicle, and the power conversion apparatusas described hereunder can perform substantially the same action in apurely electric vehicle and substantially the same effect can beobtained.

In FIG. 1, a hybrid electric vehicle (hereunder, abbreviated as “HEV”)10 is a single motor vehicle that is equipped with two vehicle drivesystems. One system is an engine system that is equipped with an engine20 that is an internal combustion engine as a motive power source. Theengine system is principally used as a driving source of the HEV. Theother system is an on-vehicle electrical equipment system that employsmotor generators 92 and 94 as a motive power source. The on-vehicleelectrical equipment system is principally used as a driving source ofthe HEV and a power generating source of the HEV. Although the motorgenerators 92 and 94 are, for example, permanent-magnet synchronousmotors, since they operate as a motor and also as a power generatordepending on the operating method, in this case they are described as“motor generator”.

A front wheel axle 14 is pivotally supported in a rotatable manner at afront portion of the vehicle body. A pair of front wheels 12 areprovided at the two ends of the front wheel axle 14. A rear wheel axle(omitted from the figure) is pivotally supported in a rotatable mannerat a rear portion of the vehicle body. A pair of rear wheels areprovided at the two ends of the rear wheel axle. In the HEV of thepresent embodiment, although a so-called “front wheel drive system” isemployed in which the front wheels 12 are taken as the main wheels to bedriven by the motive force and the rear wheels are taken as drivenwheels that are pulled around, the opposite thereof, that is, a rearwheel drive system may also be employed.

A front wheel side differential gear (hereunder, described as “frontwheel side DEF”) 16 is provided at the center portion of the front wheelaxle 14. The front wheel axle 14 is mechanically connected to the outputside of the front wheel side DEF 16. An output shaft of the transmission18 is mechanically connected to the input side of the front wheel sideDEF 16. The front wheel side DEF 16 is a differential power transfermechanism that distributes a rotational drive force that is subjected toa speed change and transmission by a transmission 18 to the right andleft of the front wheel axle 14. The output side of the motor generator92 is mechanically connected to the input side of the transmission 18.The output side of the engine 20 and the output side of the motorgenerator 94 are mechanically connected via the power transfer mechanism22 to the input side of the motor generator 92. In this connection, themotor generators 92 and 94 and the power transfer mechanism 22 arehoused inside the case of the transmission 18.

The power transfer mechanism 22 is a differential mechanism constitutedby gears 23 to 30. The gears 25 to 28 are bevel gears. The gear 23, 24,29, and 30 are spur gears. The motive power of the motor generator 92 istransferred directly to the transmission 18. The axis of the motorgenerator 92 is coaxial with the gear 29. According to thisconfiguration, when there is no supply of a driving electric power withrespect to the motor generator 92, a motive power that is conveyed tothe gear 29 is conveyed as it is to the input side of the transmission18.

When the gear 23 is driven by the operation of the engine 20, the motivepower of the engine 20 is transferred from the gear 23 to the gear 24,from the gear 24 to the gear 26 and gear 28, then from the gear 26 andgear 28 to the gear 30, and ultimately transferred to the gear 29. Whenthe gear 25 is driven by the operation of the motor generator 94, therotation of the motor generator 94 is transferred from the gear 25 tothe gear 26 and gear 28, then from the gear 26 and gear 28 to the gear30, and ultimately transferred to the gear 29. In this connection,instead of the above described differential mechanism, another mechanismsuch as a planetary gear mechanism may be used as the power transfermechanism 22.

The motor generators 92 and 94 are synchronous machines that comprise apermanent magnet in a rotor. The driving of the motor generators 92 and94 is controlled by inverter devices 40 and 42 controlling analternating current power that is supplied to an armature winding of astator. A battery 36 is electrically connected to the inverter devices40 and 42, and mutual exchange of power is possible between the battery36 and the inverter devices 40 and 42.

The present embodiment includes a first electric motor-generator unitcomprising the motor generator 92 and the inverter device 40 and asecond electric motor-generator unit comprising the motor generator 94and the inverter device 42, and divides the use of these as appropriatein accordance with the operating state. More specifically, in a case ofdriving a vehicle with the motive power from the engine 20, whenassisting the driving torque of the vehicle the second electricmotor-generator unit is operated as a power generation unit by themotive power of the engine 20 to cause it to generate power, and thefirst electric motor-generator unit is caused to operate as an electricmotor unit by the power obtained by that power generation. Further, in asimilar case, when assisting the vehicle speed the first electricmotor-generator unit is caused to operate as a power generation unit bythe motive power of the engine 20 to generate power, and the secondelectric motor-generator unit is caused to operate as an electric motorunit by the power obtained by that power generation.

Further, according to the present embodiment, by causing the firstelectric motor-generator unit to operate as an electric motor unit withthe power of the battery 36, the vehicle can be driven by only themotive power of the motor generator 92. Furthermore, according to thepresent embodiment, the battery 36 can be charged by generating power bycausing the first electric motor-generator unit or the second electricmotor-generator unit to operate as a power generation unit using themotive power from the engine 20 or the motive power from the wheels.

Next, the electrical circuit configuration of the inverter devices 40and 42 is described using FIG. 2. Although according to the embodimentshown in FIG. 1 and FIG. 2 an example is described of a case in whichthe inverter devices 40 and 42 are individually configured, aconfiguration may be adopted in which the inverter devices 40 and 42 arehoused in a single apparatus as described later using FIG. 7 and thelike. Since the inverter devices 40 and 42 have the same configurationand same action and perform the same function, in this case the inverterdevice 40 is described as an example.

A power conversion apparatus 100 according to the present embodimentcomprises the inverter device 40 and a capacitor 90, and the inverterdevice 40 has an inverter circuit 44 and a control portion 70. Theinverter circuit 44 has a plurality of upper and lower arm seriescircuits 50 (in the example shown FIG. 2, there are three upper andlower arm series circuits 50, 50, and 50) that comprise a diode 56 andan IGBT 52 (insulated gate bipolar transistor) operating as an upper armand a diode 66 and an IGBT 62 operating as a lower arm, and has aconfiguration in which an alternating current power line 86 extends froma midpoint portion (intermediate electrode 69) of each upper and lowerarm series circuit 50 through an alternating current terminal 59 to amotor generator 92. The control portion 70 has a driver circuit 74 thatdrivingly controls the inverter circuit 44, and a control circuit 72(built into the control board) that supplies a control signal to thedriver circuit 74 via a signal wire 76.

The upper arm and lower arm IGBTs 52 and 62 are power semiconductordevices for switching that operate upon receiving a driving signal thatis output from the control portion 70 to convert direct current powerthat is supplied from the battery 36 into three-phase alternatingcurrent power. This converted power is supplied to the armature windingof the motor generator 92. As described above, three-phase alternatingcurrent power that is generated by the motor generator 92 can also beconverted into direct current power.

The power conversion apparatus 100 according to the present embodimentis constituted by a three-phase bridge circuit, and is configured by theupper and lower arm series circuits 50, 50 and 50 for three phases beingrespectively electrically connected in parallel between a positiveelectrode side and a negative electrode side of the battery 36. In thiscase, each upper and lower arm series circuit 50 is referred to as an“arm”, and comprises the power semiconductor device for switching 52 andthe diode 56 on the upper arm side and the power semiconductor devicefor switching 62 and the diode 66 on the lower arm side.

According to the present embodiment an example is described in whichIGBTs (insulated gate bipolar transistor) 52 and 62 are used as powersemiconductor devices for switching. The IGBTs 52 and 62 comprisecollector electrodes 53 and 63, emitter electrodes, gate electrodes(gate electrode terminals 54 and 64), and emitter electrodes for signals(emitter electrode terminals for signals 55 and 65). The collectorelectrodes 53 and 63 of the IGBTs 52 and 62 are electrically connectedas shown in the figure between the emitter electrodes and the diodes 56and 66. The diodes 56 and 66 comprise two electrodes consisting of acathode electrode and an anode electrode. In order that the directiontoward the collector electrodes from the emitter electrodes of the IGBTs52 and 62 is the forward direction, the cathode electrodes areelectrically connected to the collector electrodes of the IGBTs 52 and62 and the anode electrodes are electrically connected to the emitterelectrodes of the IGBTs 52 and 62.

A MOSFET (metal-oxide-semiconductor field-effect transistor) may also beused as a power semiconductor device for switching. A MOSFET comprises adrain electrode, a source electrode, and a gate electrode. In thisconnection, a MOSFET comprises a parasitic diode between the sourceelectrode and the drain electrode so that the direction toward thesource electrode from the drain electrode is the forward direction. Forthis reason, it is not necessary to separately provide a diode, as withan IGBT.

The upper and lower arm series circuits 50 are provided for three phasesin correspondence with the respective phase windings of the armaturewinding of the motor generator 92. The three upper and lower arm seriescircuits 50, 50, and 50 form a U phase, a V phase, and a W phase,respectively, to the motor generator 92 through the alternating currentterminal 59 and the intermediate electrode 69 that link the emitterelectrode of the IGBT 52 and the collector electrode 63 of the IGBT 62.The upper and lower arm series circuits are connected togetherelectrically in parallel. The collector electrode 53 of the upper armIGBT 52 is electrically connected to a positive-electrode side capacitorelectrode of the capacitor 90 through a positive electrode terminal (Pterminal) 57. The emitter electrode of the lower arm IGBT 62 iselectrically connected to a negative-electrode side capacitor electrodeof the capacitor 90 through a negative electrode terminal (N terminal)58. The intermediate electrode 69 at a midpoint portion (connectionportion of the emitter electrode of the upper arm IGBT 52 and thecollector electrode of the lower arm IGBT 62) of each arm iselectrically connected through an AC connector 88 to a phase windingcorresponding to the armature winding of the motor generator 92. Asdescribed in detail later, according to the present embodiment a singleupper and lower arm series circuit 50 comprising an upper and a lowerarm is the principal circuit configuration element of a semiconductormodule.

The capacitor 90 is a device for comprising a smoothing circuit thatcontrols fluctuations in a direct-current voltage that is produced byswitching operations of the IGBTs 52 and 62. The positive electrode sideof the battery 36 is electrically connected through a DC connector 38 tothe positive-electrode side capacitor electrode of the capacitor 90, andthe negative electrode side of the battery 36 is electrically connectedthrough the DC connector 38 to the negative-electrode side capacitorelectrode of the capacitor 90. As a result, the capacitor 90 isconnected between the collector electrode 53 of the upper arm IGBT 52and the positive electrode side of the battery 36 and between theemitter electrode of the lower arm IGBT 62 and the negative electrodeside of the battery 36, and is parallelly connected electrically withrespect to the battery 36 and the upper and lower arm series circuits50.

The control portion 70 is a device for causing the IGBTs 52 and 62 tooperate. The control portion 70 comprises a control circuit 72 (builtinto the control board) that generates a timing signal for controllingswitching timing of the IGBTs 52 and 62 based on input information fromanother control device or sensor or the like, and a driving circuit 74that generates a drive signal for causing the IGBTs 52 and 62 to performa switching operation based on a timing signal that is output from thecontrol circuit 72.

The control circuit 72 comprises a microcomputer (hereunder, abbreviatedas “micon”) for processing the switching timing of the IGBTs 52 and 62.Information that is input to the micon includes a required target torquevalue with respect to the motor generator 92, a current value to besupplied to the armature winding of the motor generator 92 from theupper and lower arm series circuit 50, and a magnetic pole position ofthe rotor of the motor generator 92. The target torque value is based ona command signal that is output from an unshown high order controldevice. The current value is detected based on a detection signal thatis output from a current sensor 80. The magnetic pole position isdetected based on a detection signal that is output from an unshownrotary magnetic pole sensor that is provided in the motor generator 92.Although an example in which a three-phase current value is detected isdescribed according to the present embodiment, a configuration may alsobe adopted in which a two-phase current value is detected.

The micon inside the control circuit 72 calculates a current commandvalue for the d- and q-axis of the motor generator 92 based on thetarget torque value, calculates a voltage command value for the d- andq-axis based on a difference between this calculated current commandvalue for the d- and q-axis and a detected current value of the d- andq-axis, and converts this calculated voltage command value for the d-and q-axis into a voltage command value of the U-phase, V-phase, andW-phase based on the detected magnetic pole position. The micon thengenerates a modulated wave in a pulse shape based on a comparisonbetween a carrier wave (triangular wave) and a fundamental wave (sinewave) based on the U-phase, V-phase, and W-phase voltage command values.The micon outputs the modulated wave that is generated to the drivercircuit 74 as a PWM (pulse width modulation) signal. Six PWM signalsthat correspond to the upper and lower arms of each phase are output tothe driver circuit 74 from the micon. Another signal such as arectangular wave signal may be used as a timing signal that is outputfrom the micon.

The driver circuit 74 is configured by a so-called “driver IC” in whicha plurality of electronic circuit components are integrated in a singleintegrated circuit. Although an example of a case in which one IC isprovided for each of the upper and lower arms of each phase (1 arm in 1module: 1 in 1) is described according to the present embodiment, aconfiguration may be adopted in which one IC is provided to correspondwith each arm (2 in 1) or in which one IC is provided to correspond withall the arms (6 in 1). When driving a lower arm, the driver circuit 74amplifies a PWM signal and outputs this amplified signal as a drivesignal to the gate electrode of the corresponding lower arm IGBT 62.When driving an upper arm, the driver circuit 74 amplifies a PWM signalafter shifting the level of the reference potential of the PWM signal tothe level of the reference potential of the upper arm and outputs thisamplified signal as a drive signal to the gate electrode of thecorresponding upper arm IGBT 52. As a result, the respective IGBTs 52and 62 perform a switching operation based on the input drive signal.

The control portion 70 also performs abnormality detection (anovercurrent, overvoltage, excess temperature or the like) to protect theupper and lower arm series circuit 50. Therefore, sensing information isinput into the control portion 70. For example, from the emitterelectrode terminal for signals 55 and 65 of each arm, informationregarding the current flowing to the emitter electrodes of each of theIGBTs 52 and 62 is input into a corresponding drive portion (IC). As aresult, each drive portion (IC) performs overcurrent detection, and whenan overcurrent is detected the relevant drive portion (IC) stops theswitching operations of the corresponding IGBT 52 and 62 to protect thecorresponding IGBT 52 and 62 from the overcurrent. Information regardingthe temperature of the upper and lower arm series circuit 50 is input tothe micon from an unshown temperature sensor provided in the upper andlower arm series circuit 50. Further, information of the voltage on thedirect-current positive electrode side of the upper and lower arm seriescircuit 50 is input to the micon. The micon performs excess temperaturedetection and overvoltage detection based on these kinds of information,and when an excess temperature or overvoltage is detected, the miconstops the switching operations of all the IGBTs 52 and 62 to protect theupper and lower arm series circuit 50 (and by extension thesemiconductor module that includes the circuit 50) from the excesstemperature or overvoltage.

In FIG. 2, the upper and lower arm series circuit 50 is a series circuitof the upper arm IGBT 52 and the upper arm diode 56, and the lower armIGBT 62 and the lower arm diode 66, and the IGBTs 52 and 62 aresemiconductor devices for switching. Conduction and cutoff operations ofthe IGBTs 52 and 62 of the upper and lower arms of the inverter circuit44 are switched in a fixed sequence, and the current of the statorwinding of the motor generator 92 at the time of such switching flowsthrough a circuit created by the diodes 56 and 66.

As shown in the figure, the upper and lower arm series circuit 50comprises a positive terminal (P terminal, positive electrode terminal)57, a negative terminal (N terminal 58, negative electrode terminal), analternating current terminal 59 from the intermediate electrode 69between the upper and lower arms, an upper arm signal terminal (emitterelectrode terminal for signals) 55, an upper arm gate electrode terminal54, a lower arm signal terminal (emitter electrode terminal for signals)65, and a lower arm gate terminal electrode 64. The power conversionapparatus 100 has the DC connector 38 on the input side and the ACconnector 88 on the output side, and connects to the battery 36 and themotor generator 92 through the respective connectors 38 and 88.

FIG. 3 is a view illustrating the circuit configuration of a powerconversion apparatus that uses two upper and lower arm series circuitsas circuits that generate an output of each phase of a three-phasealternating current to be output to a motor generator. When the capacityof the motor generator increases, the amount of electric power to beconverted by the power conversion apparatus increases and current valuesthat flow through upper and lower arm direct current circuits of eachphase of the inverter circuit 44 increase. Although it is possible todeal with an increase in the conversion power by increasing theelectrical capacity of the upper and lower arms, it is preferable toincrease the amount of production of inverter modules, and in FIG. 3 aconfiguration is adopted that deals with an increase in the amount ofelectric power to be converted by increasing the used number of invertermodule that are standardized and produced. FIG. 3 is a circuitconfiguration which increases the capacity of the inverter circuit 44 inaccordance with the capacity of the motor generator by parallellyconnecting in twos the upper and lower arm direct current circuits ofthe inverter circuit 44 as one example.

As a specific configuration of the power conversion apparatus, for theU-phase, upper and lower arm series circuits 50U1 and 50U2 areparallelly connected and respective alternating current terminals 59-1and 59-2 are connected to form a U-phase alternating current power line.For U-phase use to the motor generator, 57-1 (P1 terminal) and 57-2 (P2terminal) are provided as P terminals, 58-1 (N1 terminal) and 58-2 (N2terminal) are provided as N terminals, and 59-1 and 59-2 are provided asalternating current terminals. For the V-phase and W-phase also, therespective circuits are parallelly connected in a similar manner.

In this circuit configuration, it is preferable that the voltage isequal between each P terminal and N terminal of the upper and lower armseries circuits of each phase that are parallelly connected, forexample, the upper and lower arm series circuits 50U1 and 50U2, and thata current is uniformly distributed to each of the upper and lower armseries circuits 50U1 and 50U2. To achieve this, preferably thedistributed inductance between the parallelly connected upper and lowerarm series circuits 50U1 and 50U2 and other electrical conditions aremade equal as much as possible.

According to a power conversion apparatus of the present embodiment thatis described below, since a configuration is adopted so that asemiconductor module 50U1 having the upper and lower arm series circuit50U1 built therein is disposed adjacent to a semiconductor module 50U2having the upper and lower arm series circuit 50U2 built therein,intervals between each P terminal and N terminal of these and theterminals of a capacitor module are made equal, and electricalconditions such as connection methods and the like are matched (see FIG.13), currents flowing to the semiconductor module 50U1 having the upperand lower arm series circuit 50U1 built therein and the semiconductormodule 50U2 having the upper and lower arm series circuit 50U2 builttherein that constitute each phase, for example the U-phase, aresubstantially equal, and the terminal voltages of these semiconductormodules 50U1 and 50U2 are also substantially equal. Since the parallellyconnected upper and lower arm series circuits constituting each phase ofthe inverter circuit 44 perform switching operations at the same timing,the same signal for each phase (U-phase, V-phase, and W-phase) is sentfrom the control portion 70 to each upper and lower arm series circuitconstituting these phases.

Further, when a vehicle has two motor generators as shown in FIG. 1, thevehicle will have two sets of the power conversion apparatus shown inFIG. 2 or FIG. 3. Whether the power conversion apparatus in questionwill be the circuit shown in FIG. 2 or the circuit shown in FIG. 3 will,as described above, be decided according to the specifications of themotor generator. When the circuit shown in FIG. 2 is insufficient withrespect to the power of the motor generator, the number of semiconductormodules standardized as in FIG. 3 that are used is increased to dealwith the insufficiency. Although a configuration may be adopted in whichthe respective power converters shown in FIG. 2 and FIG. 3 are providedwith respect to two motor generators, providing two inverter circuits ina single power conversion apparatus to provide a semiconductor modulecomprising two inverter circuits in a single channel case makes theoverall size far smaller than when providing two power conversionapparatuses. From a productivity and reliability viewpoint, this is alsoa superior configuration to providing two power conversion apparatuses.This kind of power conversion apparatus that comprises two invertercircuits is described later using FIG. 7.

Next, a fabrication method and structure of a semiconductor module for apower conversion apparatus according to the embodiment of the presentinvention will be described in detail while referring to FIG. 18 to FIG.28. FIG. 18 is a view that shows the external appearance of asemiconductor module with heat radiating fins having a built-in upperand lower arm series circuit in a power conversion apparatus accordingto the present embodiment. FIG. 19 is a sectional view of thesemiconductor module shown in FIG. 18. FIG. 20 is an expansion plan of asemiconductor module including a case. FIG. 21 is a sectional view ofthe semiconductor module shown in FIG. 20.

FIG. 22 is a view that illustrates in an oblique perspective manner theinternal structure of a semiconductor module relating to the presentembodiment by showing a developed view of heat radiating fins (A side)on one side of the semiconductor module and heat radiating fins (B side)on the other side thereof. FIG. 23 is a view that illustrates thestructure of an upper and lower arm series circuit that is adhered tothe inside of the heat radiating fins (A side) of the semiconductormodule. FIG. 24 is an oblique perspective view that illustrates thestructure of an upper and lower arm series circuit that is adhered tothe inside of the heat radiating fins (B side) of the semiconductormodule. FIG. 25 is an oblique perspective view that illustrates thestructure of an upper and lower arm series circuit that is adhered tothe inside of the heat radiating fins (A side) of the semiconductormodule. FIG. 26 is a front view of the structure shown in FIG. 25. FIG.27 is an oblique perspective view that shows a wire bonding state and astructure of a conductor plate that is bonded by a vacuumthermocompression method to the inside of heat radiating fins of thesemiconductor module. FIG. 28 is an explanatory view of vacuumthermocompression bonding of a conductor plate via an insulating sheetto heat radiating fins of the semiconductor module.

In FIGS. 18 to 21, a semiconductor module 500 relating to the presentembodiment comprises heat radiating fins (A side) 522 on one side (theterm “heat radiating fins” refers to not just a fin-shaped portion, butto the entire heat radiating metal), heat radiating fins (B side) 562that is on the other side, an upper and lower arm series circuit 50 thatis sandwiched between the two heat radiating fins 522 and 562, variousterminals including a positive electrode terminal 532, a negativeelectrode terminal 572, and an alternating current terminal 582 of theupper and lower arm series circuit, and a top case 512, a bottom case516, and a side case 508. As shown in FIG. 19 and FIG. 20, in a state inwhich upper and lower arm series circuits on conductor plates that arerespectively adhered through an insulating sheet to the heat radiatingfins (A side) 522 and the heat radiating fins (B side) 562 (thefabrication method is described later) are sandwiched between the heatradiating fins (A side) 522 and the heat radiating fins (B side) 562,the bottom case 516, the top case 512, and the side case 508 areattached and a mold resin is filled from the top case 512 side into thearea between the two heat radiating fins 522 and 562 to form thesemiconductor module 500 as an integrated structure.

The external structure of the semiconductor module 500, as shown in FIG.18, is one in which the heat radiating fins (A side) and heat radiatingfins (B side) are formed bordering a cooling channel, and the positiveelectrode terminal 532 (corresponds to P terminal 57 shown in FIG. 2),the negative electrode terminal 572 (corresponds to N terminal 58 shownin FIG. 2), the alternating current terminal 582 (corresponds toalternating current terminal 59 shown in FIG. 2), a signal terminal (forupper arm) 552, a gate terminal (for upper arm) 553, a signal terminal(for lower arm) 556, and a gate terminal (for lower arm) 557 of theupper and lower arm series circuit 50 protrude from the top case 512.

The external shape of the semiconductor module 500 is a substantiallyrectangular solid shape, in which the area of the heat radiating fins (Aside) 522 and the heat radiating fins (B side) 562 is large, and whenthe surface of the heat radiating fins (B side) is taken as the frontsurface and the heat radiating fins (A side) is taken as the rearsurface, the two side surfaces consisting of the side having the sidecase 508 and the opposite side thereto as well as the bottom surface andtop surface are narrow in comparison to the aforementioned front surfaceand rear surface. Since the basic shape of the semiconductor module is asubstantially rectangular solid shape and the heat radiating fins (Bside) and (A side) are square, cutting is facilitated. Further, thesemiconductor module has a shape which makes it hard to tumble over onthe production line and is thus excellent in terms of productivity.Furthermore, the ratio of the heat radiating area to the overallcapacity is large, and thus the cooling effect is improved.

In this connection, according to the present embodiment, in the heatradiating fins (A side) 522 and the heat radiating fins (B side) 562, ametal plate for inserting a semiconductor chip and for retaining aconductor inside the semiconductor module and a fin for dissipating heatare made with a single metal. This structure is excellent for increasingthe heat dissipation efficiency. However, although the heat dissipationefficiency will decrease slightly, a structure can also be used in whicha metal plate for inserting a semiconductor chip and for retaining aconductor inside the semiconductor module and heat radiating fins areformed as separate members and then bonded together.

Further, the positive electrode terminal 532 (corresponds to P terminal57 shown in FIG. 2), the negative electrode terminal 572 (corresponds toN terminal 58 shown in FIG. 2), the alternating current terminal 582(corresponds to alternating current terminal 59 shown in FIG. 2), thesignal terminal (for upper arm) 552, the gate terminal (for upper arm)553, the signal terminal (for lower arm) 556, and the gate terminal (forlower arm) 557 are assembled at the top surface that is one of thenarrow surfaces of the substantially rectangular solid shape. Thus thestructure is excellent in the respect of ease of insertion of thesemiconductor module 500 into a channel case. Further, the outer shapeof the top surface on which these terminals are provided is, as shown inFIG. 18, made larger than the outer shape of the bottom surface side,and thus the terminal portion that is the portion most easily damagedwhen the semiconductor module is moved on the production line or thelike can be protected. More specifically, by making the outer shape ofthe top case 512 larger than the outer shape of the bottom case 516, inaddition to the effect that the sealing properties of the coolingchannel opening that is described later are excellent, there is aneffect that the terminals of the semiconductor module can be protectedwhen manufacturing and transporting the semiconductor module and wheninstalling the semiconductor module into a channel case.

According to the disposition of the terminals as described above, thepositive electrode terminal 532 and the negative electrode terminal 572are disposed so as to face each other in a manner in which therespective sectional areas form a rectangular plate shape, and aredisposed close to one of the side surfaces of the semiconductor module.Since the positive electrode terminal 532 and the negative electrodeterminal 572 are disposed at a side surface side, the wiring to thecapacitor module is simple. Further, the connection ends of the positiveelectrode terminal 532 and the negative electrode terminal 572 and theconnection end of the alternating current terminal 582 are disposed in arespectively staggered condition in the cross direction of thesemiconductor module (direction linking the two side surfaces of thesemiconductor module). It is therefore possible to easily secure a spacein which to use an instrument for connecting the connection end of thepositive electrode terminal 532 or the negative electrode terminal 572with another component and connecting the connection end of thealternating current terminal 582 with another component on a productionline of the power conversion apparatus, making the structure excellentwith respect to productivity.

There is the possibility that a power conversion apparatus for a vehiclemay be cooled to minus 30 degrees or more as far as minus 40 degrees. Incontrast, there is the possibility that a power conversion apparatus fora vehicle may reached a temperature over 100 degrees, and in some rarecases a temperature close to 150 degrees. It is thus necessary toadequately consider thermal expansion changes over a wide usagetemperature range for a power conversion apparatus to be mounted in avehicle. The power conversion apparatus is also used in an environmentwhich is constantly subjected to vibrations. The semiconductor module500 that is described using FIG. 18 to FIG. 21 has a structure in whicha semiconductor chip is inserted between two heat radiating metals.According to this embodiment metal plates having heat radiating finswith an excellent heat dissipation function are used as one example ofthe heat radiating metals, and in the present embodiment the metalplates are described as the heat radiating fins 522 (A side) and theheat radiating fins 562 (B side).

In the aforementioned structure in which the semiconductor chip isinserted, the two sides of the aforementioned two heat radiating metalscomprise a structure that is fixed by the top case 512 and the bottomcase 516. In particular, the top case 512 and the bottom case 516 have astructure in which the above described two heat radiating metals areinserted from the outer side thereof and fixed. According to thisstructure, a force is always applied from the outer side toward theinner side of the heat radiating metals, and it is possible to prevent alarge force occurring between the two heat radiating metals in adirection that attempts to open apart the two heat radiating metals thatis cause by vibrations or thermal expansion. It is therefore possible toobtain a highly reliable power conversion apparatus that does not faileven when mounted in a vehicle over a long period.

According to the present embodiment, in addition to the above describedtwo heat radiating metals, since in this structure the aforementionedtop case 512 and bottom case 516 including the side cases are alsoinserted from the outer periphery side and fixed, reliability is furtherenhanced.

The structure adopted is one in which the positive electrode terminal532, the negative electrode terminal 572, the alternating currentterminal 582, the signal terminals 552 and 554, and the gate terminals553 and 556 of the semiconductor module are caused to protrudeexternally through a hole inside the top case 512 that is one of thecase, and this hole is then sealed with a mold resin 502. A highstrength material is used for the top case 512, and in consideration ofthe thermal expansion coefficient of the above described two heatradiating metals, a material with a thermal expansion coefficient nearthereto, for example, a metallic material, is used. The mold resin 502acts to decrease stress that is applied to the above terminals byabsorbing stress caused by thermal expansion of the case 512. Thereforethe power conversion apparatus of the present embodiment has highreliability that enables the power conversion apparatus to be used evenin a state in which there is a wide range of temperature changes asdescribed above or in a state in which vibrations are constantlyapplied.

The formation method and structure of an upper and lower arm seriescircuit (as an example, a 2 arm in 1 module structure) that is insertedbetween the two heat radiating fins 522 and 562 are described hereunderreferring to FIG. 22 and FIG. 28.

The fundamental process of the production method of the semiconductormodule relating to the present embodiment is described in order. Platesof heat radiating metal, for example, according to the presentembodiment the heat radiating fins (A side) 522 and the heat radiatingfins (B side) 562 that are metal plate comprising a fin structure areemployed as a base material, and an insulating sheet (A side) 524 and aninsulating sheet (B side) 564 are adhered by vacuum thermocompressionbonding to the respective inner sides thereof (see FIG. 28). A positiveelectrode side of a conductor plate 534 and a first conductor plate 544are adhered by vacuum thermocompression bonding to the insulating sheet524 (A side), and a negative electrode side conductor plate 574 and aconductor plate for alternating current (second conductor plate) 584 areadhered to the insulating sheet 564 (B side). Adhering of the conductorplates 534 and 544 to the heat radiating fins (A side) 522 and theinsulating sheet (A side) 524 is illustrated in FIG. 25 and FIG. 26, andadhering of the conductor plates 574 and 584 to the heat radiating fins(B side) 562 and the insulating sheet (B side) 564 is illustrated inFIG. 24.

Furthermore, a signal conductor 554 of the signal terminal (for upperarm) 552, a gate conductor 555 of a gate terminal (for upper arm) 553, asignal conductor 558 of a signal terminal (for lower arm) 556, and agate conductor 559 of a gate terminal (for lower arm) 557 are adhered tothe insulating sheet 524 (A side). The dispositional relationship ofthese components is as shown in FIG. 23.

The insulating sheet (A side) 524 and the insulating sheet (B side) 564function as insulating members that electrically insulate a conductor ora semiconductor chip comprising an upper and lower arm series circuit ofan inverter circuit and the heat radiating fins (A side) 522 or heatradiating fins (B side) 562 as described below. The insulating sheet (Aside) 524 and the insulating sheet (B side) 564 also perform a functionof forming a heat conduction path that conducts heat generated from asemiconductor chip or the like to the heat radiating fins (A side) 522or the heat radiating fins (B side) 562. The insulating member may be aninsulating plate or an insulating sheet made of resin or may be aceramic substrate. For example, in the case of a ceramic substrate thethickness of the insulating member is preferably 350 μ-meters or less,and in the case of an insulating sheet the thickness is preferably eventhinner at between 50 μ-meters and 200 μ-meters. However, for theinductance reduction that is described later, the effect is greater whenthe insulating member is thin, and thus an insulating sheet made ofresin has superior characteristics in this respect to a ceramicsubstrate.

Next, IGBT chips 538 and 547 and diode chips 542 and 550 are solderedvia solder layers 537, 541, 546, and 549 to protrusions 536, 540, 545,548 provided in the conductor plates 534 and 544 of the heat radiatingfins (A side) 522 (see FIG. 23). At this time, the positive electrodeside conductor plate 534 and the first conductor plate 544 are providedin a mutually insulated state and the IGBT chips and diode chipssoldered to the conductor plate 534 and 544. Further, as shown in FIG.2, a connecting plate 594 that connects an emitter electrode of an upperarm and a collector electrode of a lower arm is soldered to the firstconductor plate 544 in the same manner as chips 547 and 550. Theintermediate electrode 69 between the upper and lower arms (see FIG. 2)is configured by a direct-contact connection between the connectingplate 594 and the conductor plate for alternating current (secondconductor plate) 584.

Next, an emitter electrode for signals 661 of the upper arm IGBT 538that is soldered onto the conductor plate 534 of the heat radiating fins(A side) 522 and the signal conductor 554 of the signal terminal (forupper arm) 552 are connected by wire bonding, and a gate electrode 662of the upper arm IGBT 538 and the gate conductor 555 of the gateterminal (for upper arm) 553 are connected by wire bonding (see FIG.27). Likewise, an emitter electrode for signals of the lower arm IGBT547 that is soldered onto the first conductor plate 544 of the heatradiating fins (A side) 522 and the signal conductor 558 of the signalterminal (for lower arm) 556 are connected by wire bonding, and a gateelectrode of the lower arm IGBT 547 and the gate conductor 559 of thegate terminal (for lower arm) 557 are connected by wire bonding (seeFIG. 27).

As shown in FIG. 23, two semiconductor chips that comprise the upper armand lower arm are fixed to the heat radiating fins (A side) 522 as oneside of the heat radiating fins, and gate conductors 555 and 559 andsignal conductors 554 and 558 for controlling signals to thesesemiconductor chips are provided. Since semiconductor chips for theupper and lower arms and control lines thereof are fixed to oneinsulating member in this manner, work such as wire bonding to connect asignal wire and a semiconductor chip can be concentrated in theproduction process, and productivity and reliability are therebyimproved.

Further, when using the apparatus in an environment with largevibrations as in a vehicle, since the semiconductor chips and thecontrol lines that are to be wired are both fixed to one heat radiatingfins as the same member, anti-vibration characteristics are enhanced.

In the structure shown in FIG. 23, the upper arm semiconductor chip andthe lower arm semiconductor chip are adhered in the same direction, thatis, their respective collector surfaces are adhered to the insulatingsheet 524 as an insulating member. Matching the directions of thesemiconductor chips in this manner improves workability. The sameapplies with respect to the diode chips.

In the structure shown in FIG. 23, the upper arm semiconductor chip andthe lower arm semiconductor chip are disposed in a condition in whichthey are divided between the back side and the front side in the leaddirection of the terminals. As described later, this lead direction ofthe terminals matches the direction of insertion to the channel. Theupper arm semiconductor chip and the lower arm semiconductor chip aredisposed in a condition in which they are divided between the back sideand the front side in the direction of insertion to the channel. Byadopting this disposition, the layout of electrical components withinthe semiconductor module becomes systematic, and the overall size isreduced. Further, since the heat sources are systematically separated(since the on/off operations of each IGBT among the plurality of IGBTsas heat generating sources are systematically changed), the structurehas excellent heat dissipation properties. Furthermore, since the heatradiating surfaces are systematically separated, even if thesemiconductor module is subjected to a comparative reduction in size,the heat radiating surfaces act effectively to improve the coolingeffect.

Next, the heat radiating fins (B side) 562 is described. A conductorplate that is subjected to vacuum thermocompression bonding is adheredthrough the insulating sheet 564 as an insulating member to the heatradiating fins (B side) 562. As shown in FIG. 24, a conductor plate foralternating current 584 extending an alternating current terminal 582and a negative electrode side conductor plate 574 extending a negativeelectrode terminal 572 are disposed in a mutually insulated state on aninsulating sheet 564 as an insulating member, and protrusions 576, 578,586, and 588 are provided as shown in the figure on the respectiveconductor plates 574 and 584. The protrusions 576 and 586 are connectedto IGBT chips, and the protrusions 578 and 588 are connected to diodechips.

In FIG. 24, as shown in a partially enlarged view S1, D1 and D2represent the thickness of protrusions. The reason D1>D2 is that thediode chips are thicker than the IGBT chips. As shown in FIG. 23, on theinner side of the heat radiating fins (A side) 522, the emitterelectrode of the upper arm and the anode electrode of the diode arepresented in a projecting shape on the positive electrode side conductorplate 534 having the positive electrode terminal 532. Further, on theconductor plate 544, the emitter electrode of the lower arm and theanode electrode of the diode are presented in a projecting shape and aconnecting plate 594 constituting the intermediate electrode 69 ispresented in a projecting shape.

Subsequently, the heat radiating fins (A side) 522 and the heatradiating fins (B side) 562 are disposed facing each other as shown inFIG. 22, and the protrusions 586, 588, 576, and 578 on the conductorplates 574 and 584 on the heat radiating fins (B side) 562 are solderedin a condition facing the electrodes of the IGBT chips 538 and 547 andthe diode chips 542 and 550 of the heat radiating fins (A side) 522 soas to connect the electrodes. Further, the connecting plate 594 providedon the first conductor plate 544 of the heat radiating fins (A side) 522is disposed so as to face the conductor plate for alternating current584 provided on the heat radiating fins (B side) 562 and soldered. Next,the bottom case 516, the top case 512, and the side case 508 are adheredwith an adhesive to the heat radiating fins (A side) 522 and the heatradiating fins (B side) 562 that form an integrated structure (see FIG.20). Further, a mold resin is filled inside this structure from a hole513 in the top case to form the semiconductor module 500.

As shown in FIG. 22 or FIG. 24, one of the DC terminals and analternating current terminal are disposed in a single insulating member.Thus, by adopting a configuration in which a wiring member is disposedin the heat radiating fins (B side) 562 and disposition of thesemiconductor chips is concentrated in the heat radiating fins (A side)522, productivity is improved.

The positive electrode terminal 532, the negative electrode terminal572, the alternating current terminal 582, and the respective conductorplates 534, 574, and 584 inside the semiconductor module are formed asan integrated object, thereby enhancing productivity. Further, theseconductors are adhered to respective heat radiating metals through aninsulating member to enclose the semiconductor chip. As a result of areactive force of the enclosed semiconductor chip, these conductorplates receive a force in a direction that presses against therespective heat radiating metals, to thereby enhance the reliability ofthe aforementioned adhesion. Since the terminals and the respectiveconductors are formed as an integrated whole as described above,reliability relating to fixing of the terminals, and not only theconductors, is also enhanced. Accordingly, when applying thesemiconductor module of the above described structure to a powerconversion apparatus of a vehicle, a high level of reliability can beretained in an environment subjected to vibrations and the like.

Next, the achievement of low inductance by the circuit layout designedin the semiconductor module relating to the present embodiment isdescribed while referring to FIG. 34 and FIG. 35. However, first, themethod of attaching a semiconductor chip will be summarized again usingFIG. 2, FIG. 22, FIG. 24, and FIG. 25. In this case, with respect to theupper arm, on the heat radiating fins (A side) 522 a collector and acathode of a semiconductor chip comprising a diode and a IGBT aresoldered to a conductor plate 534 (Cu lead) of a positive plate as thepositive electrode terminal 532 (P terminal), and the emitter electrodeof the IGBT and the anode electrode of the diode are exposed on thesurface of the semiconductor chip. On the heat radiating fins (B side)562, protrusions 586 and 588 are provided facing the emitter electrodeand anode electrode of the heat radiating fins (A side) 522 on theconductor plate for alternating current 584 (Cu lead). At an extensionportion of the conductor plate for alternating current 584 are providedthe alternating current terminal 582 (terminal connecting to theU-phase, V-phase, or W-phase of the motor generator 92). When the heatradiating fins (A side) 522 and the heat radiating fins (B side) 562 aresuperimposed and soldered, a circuit of the upper arm 52 and 56 shown inFIG. 2 is formed to form a shape in which the alternating currentterminal 582 and the positive electrode terminal 532 protrude from thetop case 512 as shown in FIG. 18 and FIG. 22.

The basic structure of the present embodiment is described above.According to the present embodiment, in addition to the above describedupper arm (upper semiconductor chip), a lower arm (lower semiconductorchip) is also formed in the same manner on the heat radiating fins (Aside) 522 and the heat radiating fins (B side) 562. As shown in FIG. 23,as a lower arm, the IGBT 62 and the diode 66 shown in FIG. 2 aresoldered on the conductor plate 544 of the heat radiating fins (A side)522 in the same manner as for the upper arm. At this time, the conductorplate of the heat radiating fins (A side) 522 forms two upper and lowertiers, the semiconductor chips of the upper and lower arms are solderedonto the respective tiers, and the emitter electrode of the IGBT and theanode electrode of the diode are exposed on the surface thereof. On theconductor plates 574 and 584 of the heat radiating fins (B side) 562,protrusions 576, 578, 586, and 588 are provided at positions opposingthe anode electrodes and emitter electrodes of the upper and lower armsof the heat radiating fins (A side) 522, and a negative electrodeterminal 572 is provided at an extension portion of the lower tierconductor plate 574 of the heat radiating fins (B side) 562 and analternating current terminal 582 is provided at an extension portion ofthe upper tier conductor plate 584.

With this structure, the emitter electrode and the anode electrode 542of the IGBT chip 538 of the upper arm is connected to the alternatingcurrent terminal 582 through the protrusion 586 and protrusion 588.Further, the collector electrode and the cathode electrode of the IGBTchip 547 of the lower arm are connected via the conductor plate 544 andthe protrusion-shaped connecting plate 594 to the conductor plate foralternating current 584 to communicate with the alternating currentterminal 582. Furthermore, the emitter electrode 547 and anode electrode550 of the lower arm communicate with the negative electrode terminal572 through the protrusions 576 and 578. Thus, the circuit configurationshown in FIG. 2 is formed. FIG. 23 shows a butting surface of the heatradiating fins (A side) 522. FIG. 24 shows a butting surface of the heatradiating fins (B side) 562. These butting surfaces are matched andsoldered to form a principal portion of the semiconductor module.

As shown in FIGS. 18 to 28, according to the power conversion apparatusof the present embodiment, the semiconductor module 500 has a structurein which semiconductor chips are wedged between two heat radiatingmetals. According to this embodiment metal plates, heat radiating fins522 (A side) and heat radiating fins 562 (B side), having heat radiatingfins with an excellent heat dissipation function are used as one exampleof a heat radiating metal. A structure is adopted in which the IGBTchips 538 and 547 as semiconductor chips are wedged between conductorplates provided on the inner side of two heat radiating metals.According to this structure, low-temperature soldering can be used assoldering for electrical connections. When using low-temperaturesoldering, there is a possibility that after fixing a semiconductor chipto one of the heat radiating metals when a solder has melted once, theaforementioned soldered portion will melt again in a process thatsandwiches the semiconductor chip with the other heat radiating metal tomake an electrical connection.

However, as described above, since a fixing method is employed whichstrongly inserts the electrodes on both sides of the semiconductor chip,for example, according to the present embodiment the collector electrodeand emitter electrode of the IGBT chip, even if the solder layer meltsagain a problem that results in a fault does not occur. For this reason,low-temperature soldering can be used. Not only does low-temperaturesoldering lead to favorable productivity in comparison tohigh-temperature soldering, but thermal conductivity is also superiorcompared to high-temperature soldering. Therefore, by adopting astructure that can use low-temperature soldering, a semiconductor modulewith excellent heat resistance can be obtained, and a significant effectcan be obtained from the viewpoint of reliability when applied to apower conversion apparatus to be mounted in a vehicle.

As shown in FIGS. 18 to 28, according to the power conversion apparatusof the present embodiment, the semiconductor module 500 has a structurein which semiconductor chips are wedged between two heat radiatingmetals. By adopting a structure in which semiconductor chips areinserted between heat radiating metals in this manner, a powerconversion apparatus for a vehicle can be obtained which can be used inan environment in which vibrations are constantly present and for whichthe usage temperature range is extremely wide. Further, the presentembodiment has a structure in which the top sides of the above describedtwo heat radiating metals that sandwich the semiconductor chips arefixed with the top case 512, and the positive electrode terminal 532,the negative electrode terminal 572, and the alternating currentterminal 582 of the semiconductor module protrude to outside from thetop case 512. The present embodiment also has a portion in which thesectional area of the terminals narrows at the base of theaforementioned positive electrode terminal 532, the negative electrodeterminal 572, and the alternating current terminal 582 of thesemiconductor module that protrude externally. The conductors 534, 574,and 584 inside the semiconductor module of each terminal are fixed toone or the other of the heat radiating metals to provide a strongstructure with respect to vibrations. Further, although not shown in thedrawings, by providing respective portions with small sectional areasbetween the terminals that protrude externally and the inner conductors,it is possible to reduce the amount of stress produced by vibrationsfrom outside or stress produced by thermal expansion being applied as itis to the inner conductors.

Next, achievement of low inductance in the semiconductor moduleaccording to the present embodiment is described using FIG. 34 and FIG.35. Since a transient voltage rise or a large heat generation in asemiconductor chip occurs at the time of a switching operation of anupper or lower arm configuring an inverter circuit, it is preferable toreduce inductance at the time of a switching operation in particular.Since the recovery current of a diode occurs at the time of atransition, based on this recovery current the action of inductancereduction will now be described taking as one example the recoverycurrent of the diode 66 of a lower arm.

The recovery current of the diode 66 is a current that flows regardlessof the fact that the diode 66 has a reverse bias, and it is generallysaid that the recovery current is ascribable to carriers that are filledinside the diode 66 in a forward direction state of the diode 66. When aconduction operation or cutoff operation of an upper or lower armconstituting the inverter circuit is performed in a predetermined order,a three-phase alternating current power is generated in the alternatingcurrent terminal of the inverter circuit. At this time, when thesemiconductor chip 52 operating as an upper arm switches from aconducting state to a cutoff state, a return current flows through thediode 66 of the lower arm in a direction that maintains the current ofthe stator winding of the motor generator 92. This return current is aforward direction current of the diode 66, and the inside of the diodeis filled with carriers. Next, when the semiconductor chip 52 operatingas the upper arm stitches from a cutoff state to return to a conductingstate again, a recovery current ascribable to the aforementionedcarriers flows into the diode 66 of the lower arm. In routine operationseither one of the upper and lower arm series circuits is always in acutoff state, and although a state does not occur in which a shortcircuit current flows to the upper and lower arms, a transient statecurrent, for example, a recovery current of a diode, flows through aseries circuit comprising the upper and lower arms.

When an IGBT (semiconductor device for switching) 52 operating as anupper arm of the upper and lower arm series circuit in FIG. 34 and FIG.35 changes from off to on, a recovery current (indicated by an arrow inthe drawings) of the diode 66 flows from the positive electrode terminal532 (57) to the negative electrode terminal 572 (58) through the IGBT 52and the diode 66. At this time the IGBT 62 is in a cutoff state. Whenthe flow of this recovery current is observed, as shown in FIG. 34 it isfound that in the vicinity of the positive electrode terminal 532 andthe negative electrode terminal 572 conductor plates are parallellydisposed and the same current flows in reverse directions. Thus,magnetic fields produced by the current of each conductor plate in thespace between the conductor plates cancel each other out, and as aresult the inductance in the current path decreases.

More specifically, because the positive electrode side conductor 534 andterminal 532 and the negative electrode side conductor 574 and terminal572 are in a laminated state in which they are adjacent and opposinglydisposed, an inductance lowering action occurs. FIG. 35 is an analogouscircuit to FIG. 34, in which an equivalent coil 712 of the terminal 532and the conductor 534 on the positive electrode side and an equivalentcoil 714 of the terminal 572 and the conductor 574 on the negativeelectrode side act in a direction that cancels out each others' magneticflux to thereby lower the inductance.

Further, when the path of the recovery current shown in FIG. 34 isobserved, it is found that a path with a loop shape arises following thepaths of the currents that are parallel and flow in inverse directions.When a current flows through this loop-shaped path, eddy currents 605and 606 flow to the heat radiating fins (A side) and the heat radiatingfins (B side), and an action that reduces inductance in the loop-shapedpath occurs as a result of a magnetic field cancellation effect producedby these eddy currents. In the analogous circuit shown in FIG. 35, aphenomenon that produces an eddy current is equivalently represented byinductances 722, 724, and 726. Since these inductances are positionednear the metal plate that is the heat radiating fins, a relationship isentered in which magnetic fluxes produced by eddy currents generated byinduction are cancelled out, and as a result the inductance of thesemiconductor module is reduced by the eddy current effect.

As described above, according to the layout of the circuit configurationof the semiconductor module relating to the present embodiment,inductance can be reduced by the effect produced by a laminatedarrangement and the effect produced by eddy currents. Reducinginductance at the time of a switching operation is important and thusaccording to the semiconductor module of the present embodiment theseries circuit of the upper arm and the lower arm is housed inside thesemiconductor module. Therefore, there is a significant inductancelowering effect in transient state, including the fact that a lowinductance can be achieved with respect to the recovery current of adiode that flows through an upper and lower arm series circuit.

When the inductance is reduced, an induction voltage produced in thesemiconductor module decreases and it is possible to obtain a low-losscircuit configuration. An improvement in the switching speed can also beobtained as a result of the low inductance. Further, as described laterreferring to FIG. 31, when adopting a configuration for achieving alarge capacity by disposing a plurality of semiconductor modules 500comprising the above described upper and lower arm series circuits 50 inparallel and connecting them with each capacitor 90 inside the capacitormodule 95, the effects of variations in the inductance produced by thesemiconductor modules 500 inside the power conversion apparatus 100decrease because of a reduction in the inductance of the semiconductormodules 500 themselves, and the operation of the inverter device isstable.

Further, when it is desired to achieve a large capacity (for example,400 A or more) for a motor generator, it is necessary to also providethe capacitor 90 with a large capacity, and as shown in FIG. 31, when alarge number of individual capacitors 90 are parallelly connected andcapacitor terminals 96 are disposed in a parallel condition as shown inthe figure, the positive electrode terminal 532 and negative electrodeterminal 572 of the respective semiconductor modules are connected atequal distances with respective capacitor terminals 96. As a result, acurrent flowing to each of the semiconductor modules is equallydistributed, making it possible to achieve well-balanced, low-loss motorgenerator operations. Further, as a result of the parallel dispositionof the positive electrode terminal and negative electrode terminal ofthe semiconductor module, together with the reduction in inductance bythe laminated effect, low-loss operations can be performed.

Next, the specific contents disclosed in the drawings will be describedfor a configuration example of the power conversion apparatus accordingto the present embodiment. FIG. 18 is a view that shows the externalappearance of a semiconductor module with heat radiating fins relatingto the present embodiment. FIG. 19 is a sectional view of thesemiconductor module shown in FIG. 18 when the section indicated byalternate long and short dashed lines is viewed from the direction ofthe arrows. FIG. 20 is an expansion plan of the semiconductor modulerelating to the present embodiment that shows various terminals of theupper and lower arm series circuit, heat radiating fins and cases. FIG.21 is a view of the semiconductor module shown in FIG. 20 when thesection indicated by alternate long and short dashed lines is viewedfrom the direction of the arrows, which shows a state in which the heatradiating fins 522 and 562 are adhered by adhesion of the bottom case516 and the top case 512. FIG. 22 is an expansion plan that showssoldering of an IGBT chip, a diode chip and a connecting plate providedon the conductor plate of the heat radiating fins (A side) withprotrusions of the conductor plate of the heat radiating fins (B side)in the semiconductor module relating to the present embodiment.

FIG. 23 is a view that shows the specific structure according to whichan IGBT chip, a diode chip, and a connecting plate are disposed on theconductor plate of the heat radiating fins (A side). The details thereofare as described above. FIG. 24 is a view showing the specificdisposition of protrusions on the conductor plate on the heat radiatingfins (B side), in which the fact that there is a difference in thethicknesses D1 and D2 of the protrusions in the partially enlarged viewS1 is as described above. FIG. 25 is an oblique perspective view showingthe specific disposition of protrusions on the conductor plate of theheat radiating fins (A side), in which S2 denotes a partially enlargedview. In S2, reference characters D3 denote the thickness of aprotrusion 540, reference characters D4 denote the thickness of aprotrusion 536, and reference characters D5 denote the thickness of aprotrusion 592. The reason these thicknesses differ is to compensate forthe differences in the thicknesses of the diode chip, the IGBT chip, andthe connecting plate 594. FIG. 26 is a front view of the structure shownin FIG. 25. FIG. 27 is a view that shows a state in which the conductorplate of the heat radiating fins (A side) and the conductor plate of theheat radiating fins (B side) overlap each other, and shows a wirebonding state between the signal conductor 554 and gate conductor 555and the emitter electrode terminal 661 and gate electrode terminal 662in the IGBT of the upper and lower arm series circuit. FIG. 28 is a viewshowing vacuum thermocompression bonding of the insulating sheets 524and 564 to the heat radiating fins 522 and 562.

In FIG. 23 and FIG. 27, the emitter electrode 538 of the upper arm 52 isillustrated as a rectangular shape, and at an upper portion thereof at adistance from the rectangular-shaped emitter electrode 538 are formedthe emitter electrode terminal for signals 661 (corresponds to symbol 55in FIG. 2) and the gate electrode terminal 662 (corresponds to symbol 54in FIG. 2). As described above, the emitter electrode terminal forsignals 661 and the signal conductor 554 are subjected to wire bonding,and the gate electrode terminal 662 and the gate conductor 555 aresubjected to wire bonding. On the heat radiating fins (B side) 562, aconcave-shaped conductor plate for alternating current 584 is formed soas to cover the rectangular-shaped emitter electrode 538. The emitterelectrode terminal for signals 661 and the gate electrode terminal 662are exposed through this concave hollow portion. In the configurationexample shown in FIG. 23 and FIG. 27, the rectangular-shaped emitterelectrode 538 provided on the heat radiating fins (A side) 522 and theconcave shaped conductor plate for alternating current 584 provided onthe heat radiating fins (B side) 562 are shown.

The emitter electrode 538 and the conductor plate for alternatingcurrent 584 shown in the enlarged display view surrounded by a dottedline frame in FIG. 27 effect improvements in terms of current capacityand heat release with respect to the shape of an emitter electrode of anIGBT chip. The improvements produced by this change in shape will bedescribed using FIG. 41. In a normal IGBT, as shown in FIG. 23, anemitter electrode has a substantially square shape, and on the outsidearea of this square shape are provided the emitter electrode terminalfor signals 661, the gate electrode terminal 662 and, as necessary,other electrodes. In this case, as shown in FIG. 24, the substantiallysquare emitter electrode and the conductor 574 or the conductor 584 areelectrically connected.

In FIG. 27 and FIG. 41 the proportion of the area of the emitterelectrode 538 on the IGBT chip 52 is increased. More specifically,instead of the rectangular shape shown in FIG. 23, the area of theemitter electrode is formed in a concave shape to expose only theemitter electrode for signals 661 and the gate electrode 662, and theemitter electrode terminal for signals 661 and the gate electrodeterminal 662 and, as necessary, other electrodes are provided in thisconcave area. Further, in order that the enlarged emitter electrodehaving a concave portion electrically connects with the conductor platefor alternating current 584 or the conductor 574, a concave portion isalso provided in the conductors 584 and 574 to adopt a configurationthat enlarges the connection area with the emitter electrode. As aresult of this area enlargement of the emitter electrode, the currentdensity of the emitter of the IGBT chip 52 drops and the heat radiatingarea also increases. Further, to enhance thermal diffusion, the area ofthe conductor plates 584 and 574 is enlarged by providing the conductorplate for alternating current 584 and the conductor 574 in a concaveshape such that they face the concave-shaped outer edge of the emitterelectrode 538 having the enlarged area (in comparison with the conductorplates for alternating current 584 and 574 shown in FIG. 24 that do nothave a concave shaped hollow portion in a shape corresponding to theemitter electrode, the conductor plates in FIG. 27 and FIG. 41 have ahollow portion).

Next, the connection between the semiconductor module and the capacitormodule relating to the present embodiment is described while referringto FIG. 31, FIG. 32, and FIG. 33. In this case, although the capacitormodule may be configured with a single electrolytic capacitor or filmcapacitor, since it is preferable to obtain a larger capacity with asmall volume, a configuration in which a plurality of electrolyticcapacitors or film capacitors are electrically connected in parallel ispreferred. Further, by parallelly connecting a plurality of unitcapacitors and covering the outer side thereof with a metal withexcellent heat dissipation properties, a small sized capacitor modulewith high reliability can be obtained. In comparison to a filmcapacitor, the amount of generated heat of an electrolytic capacitor islarge and in particular the effect thereof is large.

Further, by covering the outside with a metal, fixation of the unitcapacitors that are inside the capacitor module to the inside of thepower conversion apparatus is strengthened, and is strong with respectto vibrations. For example, frequencies of various components areincluded in vibrations of a vehicle and there is a risk that the unitcapacitors within the aforementioned capacitor module will resonate. Itis therefore preferable to firmly fix one or a plurality of unitcapacitors within the capacitor module and, as described later, to alsofirmly fix the capacitor module inside the power conversion apparatusand, for example, to firmly fix the apparatus in a channel case.

FIG. 31 is a view showing connection terminals of a capacitor module ofthe power conversion apparatus according to the present embodiment. FIG.32 is an oblique perspective view illustrating a connection statebetween a capacitor module and a semiconductor module relating to thepresent embodiment, and FIG. 33 is a sectional view illustrating thisconnection state. In the figures, reference numeral 390 denotes acapacitor module, reference numeral 96 denotes a capacitor terminal,reference numeral 611 denotes a capacitor positive electrode terminal,reference numeral 612 denotes a capacitor negative electrode terminal,reference numeral 613 denotes an insulation guide, reference numeral 533denotes a positive electrode terminal comb of the semiconductor module,reference numeral 573 denotes a negative electrode terminal comb of thesemiconductor module, and reference numeral 630 denotes an insertionopening.

In the example illustrated in the drawings, the capacitor module 390 isprovided with capacitor terminals 96 that respectively correspond withthe U-phase, V-phase, and W-phase of the motor. Respective capacitors 90are provided inside the capacitor module in correspondence with thenumber of terminals 96.

The positive electrode terminal 611 and the negative electrode terminal612 of the capacitor terminal 96 are formed in a comb shape as shown inthe drawings, similarly to the comb shapes 533 and 573 of the positiveelectrode terminal 532 and the negative electrode terminal 572 of thesemiconductor module 390. By making the connection terminals of both thecapacitor module 390 and the semiconductor module in a comb shape,welding and other adhesive connections are facilitated between theconnection terminals of the capacitor module 390 and the semiconductormodule. Further, an insulation guide 613 is provided at a center part ofthe terminals of the capacitor module 390. The insulation guide 613provides insulation between the positive electrode terminal 611 and thenegative electrode terminal 612, and by inserting the insulation guide613 into the insertion opening 630 of the semiconductor module theinsulation guide 613 also performs a guide function for connectingtogether the connection terminals of the capacitor module and thesemiconductor module.

According to the present embodiment, a DC terminal of the capacitormodule 390 is provided in correspondence with each direct current sideterminal of the semiconductor module 500, and inductance is reducedbetween the terminals of the capacitor module 390 and the terminals ofthe semiconductor module. Although it is preferable from an inductancereduction viewpoint to directly connect the terminals of the capacitormodule and the terminals of the semiconductor module, as in the presentembodiment, a situation may be considered in which the capacitor moduleand the semiconductor module can not be adjacently disposed. As shown inFIG. 2 and FIG. 3, the capacitor and each upper and lower arm seriescircuit of the inverter circuit are in a parallelly connectedrelationship and, for example, a configuration may be adopted in which adirect current bus bar that is disposed facing the DC positive electrodeconductor and the DC negative electrode conductor is used, one end ofthe direct current bus bar is connected to the positive electrodeterminal 611 and the negative electrode terminal 612 of the capacitormodule 390, and the other end of the direct current bus bar is connectedto the positive electrode terminal 532 and the negative electrodeterminal 572 of the semiconductor module. By disposing the conductors inan opposing condition as close as possible to each other so that therespective magnetic fluxes generated by the DC positive electrodeconductor and the DC negative electrode conductor comprising the directcurrent bus bar cancel each other out, an inductance increase can besuppressed.

In a case in which each phase of a inverter circuit is configured with aplurality of upper and lower arm series circuit that are parallellyconnected as shown in FIG. 3, even when using the above described directcurrent bus bar it is preferable that the parallelly connected pluralityof upper and lower arm series circuits constituting each phase areplaced in electrically equivalent conditions. Accordingly, on thesemiconductor module side of the aforementioned direct current bus bar,it is preferable that respective connection terminals are provided incorrespondence with terminals of the semiconductor module thatconstitute each phase, and preferably the shape of those terminals islike the shape of the terminals 96 shown in FIG. 31.

Next, the cooling situation of the semiconductor module relating to thepresent embodiment is described hereunder while referring to FIG. 29 andFIG. 30. FIG. 29 is a view that represents the flow of cooling water ofthe heat radiating fins (A side) in a semiconductor module related tothe present embodiment. FIG. 30 is a view that represents the relationbetween the cooling water flow and the layout of the circuitconfiguration in the semiconductor module shown in FIG. 30. In thefigures, reference numeral 622 represents the flow of cooling water inthe upper tier of the semiconductor module and reference numeral 623represents the flow of cooling water in the lower tier of thesemiconductor module.

As described above, inside the semiconductor module relating to thepresent embodiment, the IGBT chip 52 of the upper arm as a heatingelement and the diode chip 56 are disposed in the same series shape onthe upper tier, and the IGBT chip 62 of the lower arm as a heatingelement and the diode chip 66 are disposed in the same series shape onthe lower tier. In this case, the upper tier corresponds to the frontside in the insertion direction of the semiconductor module 500 to thecooling channel, and the lower tier corresponds to the back side in theaforementioned insertion direction.

In addition to a heat exchanging function with the cooling water, thesemiconductor module 500 has an action that keeps the cooling water in alaminar flow state and also guides the cooling water in a predetermineddirection. According to the present embodiment, normally the coolingwater forms a horizontal flow along a concave portion (groove) of theconcavo-convex shaped heat radiating fins. The cooling water 622 thatflows into the upper tier absorbs heat that is generated at the diodechip 56 and the IGBT chip 52 as shown by the dotted line, and forms areturn path through a fin concave portion of the heat radiating fins (Bside) as shown by the solid line. Likewise, the cooling water 623 thatflows into the lower tier absorbs heat that is generated at the IGBTchip 62 and the diode chip 66, without receiving the influence of heatgenerated from the upper tier semiconductor chips 52 and 56. Thus, byadopting a semiconductor module structure in which semiconductor chipscomprising the diode chip and the IGBT chip that are heating elementsare differently disposed in upper and lower tiers, the water-coolingeffect is augmented.

Next, an outline regarding cooling of the semiconductor module relatingto the present embodiment is initially described. As shown in FIG. 18and FIG. 19, the semiconductor module 500 has built therein an upper andlower arm series circuit 50 including semiconductor chips 52, 56, 62,and 66 of the upper and lower arms that is wedged between the facingheat radiating fins (A side) and heat radiating fins (B side), and isinserted into a channel case 212 shown in FIG. 16 and FIG. 17. Thesemiconductor module is configured to be cooled by flowing water on thetwo surfaces of heat radiating plates forming heat radiating fins of thesemiconductor module 500. More specifically, a two-sided coolingstructure is used in which semiconductor chips as heating elements arecooled from two surfaces consisting of the heat radiating fins (A side)522 and the heat radiating fins (B side) 562 by cooling water.

In this case, considering the changes regarding cooling of semiconductormodules, although there is a trend that the cooling methods have developfrom single-sided indirect cooling systems to single-sided directcooling systems to two-sided indirect cooling systems and onto two-sideddirect cooling systems, in the current cooling systems a structure isoften observed in which a plurality of semiconductor devices forswitching (IGBT) that are heating elements are provided, these areparallelly connected (to disperse generated heat that the semiconductordevices carry), and a group of parallelly connected semiconductordevices are mounted on a heat radiating plate via a grease layer and aninsulating layer. According to this current cooling system, one-sidedcooling is performed by a providing a heat radiating plate on one sideof the group of semiconductor devices, and indirect cooling is carriedout by putting grease between the group of semiconductor devices and theheat radiating plate. Although the grease is originally provided for thepurpose of adhering a conductor plate with an insulating layer (Cu leadmounting a group of semiconductor devices) to the heat radiating plate,it is necessary to tightly fix the plate with a screw since thethickness becomes uneven. Although the thermal conductivity of thegrease is good, the grease has drawbacks with regard to adhesiveness,thickness uniformity, and insulating properties.

Since the present embodiment has various improvements, for example asshown in FIG. 29 and FIG. 30, even for an indirect cooling system usingthe aforementioned grease, the heat dissipation effect is improvedcompared to the conventional system, and various other effects can beobtained as described above. As will be described below, since asemiconductor chip is fixed to a metal for heat dissipation through aninsulating member, the heat dissipation effect is improved further.Examples of the insulating member include a ceramic plate or aninsulating sheet made of resin, and by fixing the semiconductor chip tothe heat radiating metal via these, the heat conduction properties areimproved and the heat dissipation effect is improved. In comparison to aceramic plate, the insulating sheet described below has a thinnerthickness and thus can produce a larger effect.

The power conversion apparatus according to the embodiment of thepresent invention employs a two-sided direct cooling system in whichcooling is conducted from both sides of the semiconductor module and,without using grease, an insulating sheet is placed between a heatradiating plate and a conductor plate on which semiconductor chips aremounted to perform vacuum thermocompression bonding, and thus thecooling capability can be improved. According to the present embodiment,as described above with reference to FIG. 28 and FIG. 23, the two-sideddirect cooling system is achieved by initially bonding insulating sheetsfor heat dissipation 524 and 564 (for example, insulating resin with athickness of 100 to 350 mm) by a vacuum thermocompression bonding toheat radiating fins (heat radiating plates) 522 and 562 comprising Cu orAl, then performing vacuum thermocompression bonding again between theinsulating sheets and conductor plates 534, 544, 574 and 584 (forexample Cu lead) having positive electrode and negative electrodeterminals 532 and 572, and subsequently attaching semiconductor chips bysoldering to the conductor plates and water cooling the two sides of thesemiconductor module 500 through the heat radiating fins as shown inFIG. 29. In this case, in comparison to grease, the insulating sheetshave superior properties with respect to adhesiveness, uniformity ofthickness, and insulating properties.

Next, a specific configuration of a power conversion apparatus having acooling function according to the embodiment of the present inventionwill be described while referring to FIG. 4 to FIG. 7. FIG. 4 is a viewthat illustrates the external shape of the power conversion apparatusaccording to the embodiment of the present invention. FIG. 5 is anexploded view that gives a perspective view of the internal structure ofthe power conversion apparatus according to the present embodiment. FIG.6 is an oblique perspective view of a state in which an upper case isremoved from the power conversion apparatus according to the presentembodiment. FIG. 7 is an oblique perspective view of a state in which anupper case, a control board 370 containing a control circuit 72, and abus bar assembly are removed from the power conversion apparatusaccording to the present embodiment.

In the drawings, the power conversion apparatus 100 has a structurehaving a plurality of semiconductor modules 500 mounted in the channelcase 212, and having a control board 372 on which driver ICs 374 aremounted and which has a driver circuit 74 built therein. Further, acapacitor module 390 (component corresponding to reference numeral 95shown in FIG. 31) and a bus bar assembly 386 are mounted thereon, thestructure comprises a connector portion 280 including the DC connector38 and the AC connector 88 (see FIG. 2), has an inlet portion 246 and anoutlet portion 248 of a channel, and is enclosed by the lower case 142,the upper case 112, and the cover 132. In this connection, the bus barassembly 386 includes a direct current bus that connects the capacitormodule 390 and the DC terminals and DC connector 38 of the semiconductormodule 500, and an alternating current bus that connects the alternatingcurrent terminal 582 and the AC connector 88 of the semiconductor module500.

Referring to FIG. 7 and FIG. 8, the channel case 212 is broadly dividedinto a channel case main unit 214, a channel case front portion 224, anda channel case rear surface portion 234, and has the channel inletportion 246 and the outlet portion 248. A control circuit connector 373and a driver IC 374 are mounted on the control board 372. In the exampleshown in FIG. 7, the negative electrode terminal 572, the positiveelectrode terminal 532, and the alternating current terminal 582 of thesemiconductor module are protruding, and the negative electrode andpositive electrode terminals 572 and 532 are connected with a capacitorterminal of the capacitor module 390 (see FIG. 6 and FIG. 32). In theconfiguration example shown in FIG. 7, six upper and lower arm seriescircuits 50 (principal circuits of the semiconductor module 500) areloaded in correspondence with the circuit configuration of the inverterdevice 40 shown in FIG. 3. More specifically, two upper and lower armseries circuits are used for the respective U, V, and W phases of themotor to achieve a large capacity to the motor generator 92.

A configuration example in which another unit of the inverter device 40shown in FIG. 3 is parallelly connected to the battery 36 and eachinverter device is connected to respective motor generators to form anapparatus in which two inverter devices supplying power to two motorgenerators are housed in one channel case 212 is shown in FIG. 8, FIG.9, and FIG. 10. In this connection, the configuration example shown inFIG. 8, FIG. 9, and FIG. 10 is not limited to a power supply to twomotor generators. FIG. 8 is an oblique perspective view showing aconfiguration example of two inverter devices in the power conversionapparatus according to the present embodiment, which shows a state inwhich the control board 370 containing the control circuit 72, the busbar assembly, and the upper case are removed. FIG. 9 is an obliqueperspective view showing a configuration example of two inverter devicesin the power conversion apparatus according to the present embodiment,which shows a state in which the control board 370 containing thecontrol circuit 72, the bus bar assembly, the upper case and thecapacitor module are removed. FIG. 10 is a plan view showing aconfiguration example of two inverter devices in the power conversionapparatus according to the present embodiment, which shows a state inwhich the control board 370 containing the control circuit 72, the busbar assembly, the upper case and the capacitor module are removed. Inthis connection, in FIG. 8, a bus bar assembly 386 is disposed on anupper portion of the control board 372 and is disposed between the twosets of capacitor modules 390.

Referring to FIG. 8, FIG. 9, and FIG. 10, the two sets of semiconductormodules 500 are inserted into the channel case 212 in a state in whichthey are rotated 180 degrees. The capacitor modules 390 are alsodisposed in a state in which they are rotated 180 degrees. The controlboard 372 having the in-built driver circuit 74 comprises a singe boardthat is disposed between each set of semiconductor modules 500. It isalso possible to provide only one of the control circuit connector 373as a common component for the two sets of semiconductor modules. Theupper and lower arms of each phase are driven with a single driver IC374, and each phase is configured by two series circuits in which theupper and lower arms are parallelly connected (see FIG. 3). Concurrentcontrol signals are supplied to the parallelly connected upper and lowerarm series circuits from the single driver IC 374.

The control board having the driver circuit is disposed at a position onthe opposite side to the capacitor module 390 with respect to thealternating current terminal, and the control terminal of thesemiconductor switching device comprising upper and lower arms isdisposed at a position on the opposite side to the capacitor module withrespect to the alternating current terminal. According to thisconfiguration, the electrical connection between the capacitor module390 and the semiconductor modules and the electrical connectionrelationship between the control terminal and the control board 372having the driver circuit 74 are in an orderly state, leading toreduction in the size of the power conversion apparatus.

Further, in the power conversion apparatus having two inverter devices,by disposing the control board 372 having a driver circuit 74 in thecenter as shown in FIG. 10, it is possible to provide two drivercircuits 74 for controlling two inverter devices on a single controlboard 372, leading to a reduction in the size of the power conversionapparatus and also improvement in productivity.

Next, the method of loading semiconductor modules into a channel caseaccording to the power conversion apparatus of the present embodimentand the situation regarding the cooling water flow in the channel casein which semiconductor modules are loaded will be described referring toFIG. 11 to FIG. 17.

FIG. 11 is a sectional view that illustrates the flow of cooling waterin a channel case in which semiconductor modules are loaded that relatesto the present embodiment. FIG. 12 is a sectional view showing the flowof cooling water in a channel case in which semiconductor modules areloaded with respect to the two inverter devices shown in FIG. 9. FIG. 13is a plan view that shows the disposition situation in a channel case ofa positive electrode terminal, a negative electrode terminal, analternating current terminal, a signal terminal, and a gate terminal ofsemiconductor modules that are parallelly connected for each phase tothe motor generator shown in FIG. 3. FIG. 14 is an oblique perspectiveview that illustrates a channel case main unit in which semiconductormodules are loaded, a channel case front surface portion, and a channelcase rear surface portion. FIG. 15 is a sectional view that illustratesa channel case main unit in which semiconductor modules are loaded, achannel case front surface portion, and a channel case rear surfaceportion. FIG. 16 is an oblique perspective view that illustrates a statein which semiconductor modules are being loaded in the channel case mainunit. FIG. 17 is a front view that illustrates a state in whichsemiconductor modules are being loaded in the channel case main unit.

In FIG. 11 and FIG. 12, reference numeral 212 denotes a channel case,reference numeral 214 denotes a channel case main unit, referencenumeral 224 denotes a channel case front portion, reference numeral 226denotes a front portion inlet channel, reference numeral 227 denotes afront portion loopback channel, reference numeral 228 denotes a frontportion outlet channel, reference numeral 234 denotes a channel caserear surface portion, reference numeral 236 denotes a rear surfaceportion loopback channel, reference numeral 246 denotes an inletportion, reference numeral 248 denotes an outlet portion, and referencenumerals 250 to 255 denote water flows.

As shown in FIG. 6 and FIG. 14 that is described later, a front portioninlet channel 226 and a front portion outlet channel 228 are providedbetween the inlet portion 246 and outlet portion 248 and the main unit214 linking these (see FIG. 11), and the channel height of thesechannels 226 and 228 corresponds to the height of the semiconductormodule 500 (see water conveyance portion 249 in FIG. 14). Accordingly,the height of the water flow 250 from the inlet portion 246 increases inthe front portion inlet channel 226, and water flows across the totalheight of the heat radiating fins 522 and 526 of the semiconductormodules 500 loaded in the main unit 214. The water flow indicated byreference numerals 251, 236, 253, and 227 shown in FIG. 11 will now bedescribed. The cooling water flows across the total height of the heatradiating fins (B side) 562 of the semiconductor module 500 (water flow251), passes through the loopback channel 236 of the rear surfaceportion 234, flows across the total height of the heat radiating fins (Aside) (water flow 253), and passes through the loopback channel 227 ofthe front portion 224 to flow to the next semiconductor module 500.Thus, the semiconductor modules 500 are subjected to two-sided cooling.

FIG. 12 illustrates a structure in which, as shown in FIG. 9 and FIG.10, semiconductor modules for two inverter devices are loaded in asingle channel case and cooled. In FIG. 12, six semiconductor modules500-1 are used for one of the inverter devices and six semiconductormodules 500-2 are used for the other of the inverter devices. As shownin FIG. 12, the semiconductor modules 500-1 and 500-2 are arranged in acascade manner along the direction of the water flows 251 and 253 of thechannel case main unit 214.

According to the present embodiment a structure is adopted in which anopening that communicates with the channel is provided in the channelcase 212, and the semiconductor modules 500 are inserted into theopening. It is thereby possible to produce the semiconductor modules 500on an electronic circuit production line and then fix the semiconductormodules 500 in the channel case after undergoing the necessaryinspections. This leads to an improvement in productivity as well as animprovement in reliability.

Further, a cooling fin with a wide area is provided on both sides of thesemiconductor modules 500, and the flow of a water flow is created withthe cooling fins. More specifically, channels that flow in inversedirections are formed by inserting the semiconductor modules 500 intothe channel, and the aforementioned cooling fins perform an action ofnot only dissipating heat but also creating laminar flows in inversedirections, and act to form channels. The channel case is made, forexample, by die casting, and a wide section of the channel is formed bythe fins of the above described semiconductor modules 500. Accordingly,productivity improves.

Channels that flow in inverse directions are formed by inserting thesemiconductor modules 500 into the channel, and the channel sectionalarea narrows. If it is assumed that the amount of feeding water is thesame, the flow rate is increased by making the sectional area smaller.Thus, the cooling efficiency increases.

FIG. 14 illustrates a situation in which all of six semiconductormodules 500 are loaded in a channel case in a case in which thesemiconductor modules are parallelly connected with respect to eachphase to a motor generator (see the circuit configuration shown in FIG.3). FIG. 16 and FIG. 17 illustrate a situation in which thesemiconductor modules 500 are loaded in sequence into the main unit 214of the channel case 212. The channel case main unit 214 comprisespartition walls 271 that separate a channel forming portion 270 and achannel forming portion 270. The semiconductor modules 500 are loadedinto the channel forming portions 270 from above. An adhesive is appliedonto an upper edge portion of the top case 512 of the semiconductormodule 500 and/or the channel forming portion 270 to fix these twocomponents. As shown in the figure, since the channel forming portion270 and the heat radiating fins 522 and 562 of the semiconductor module500 are substantially the same size, the cooling water flows along therecesses in the fins.

As shown in FIG. 14, following the channel inlet portion 246, the frontportion 224 of the channel case 212 comprises a water conveyance portion249 that has substantially the same bulk as the channel forming portion270 of the main unit 214 (see FIG. 16). By means of this waterconveyance portion 249, a substantially uniform water flow is formedacross the entire height of the semiconductor module 500.

As shown in FIG. 14 and FIG. 15, by dividing the channel case 212 intothe main unit 214, the front portion 224, and the rear surface portion234, the main unit has a shape in which spaces to become channels opento the front surface side and the rear surface side, and a die castingmanufacturing process using aluminum as a material is possible. A diecasting manufacturing process can also be used for the front portion 224and the rear surface portion 234, and thus productivity improves.

FIG. 13 shows the structure of the arrangement with respect to thechannel case 212 for the six semiconductor modules 500 in a case inwhich the semiconductor modules are parallelly connected for each phaseto the motor generator (see circuit configuration of FIG. 3). The upperand lower arm series circuits 50 shown in FIG. 3 are arranged as shownin the figure as circuits 50U1 and 50U2 for the U-phase, circuits 50V1and 50V2 for the V-phase, and circuits 50WU1 and 50W2 for the W-phase.As shown in FIG. 31 and FIG. 32, the capacitor terminals 96 of thecapacitor module are disposed in the same direction as the arrangementdirection of the positive electrode terminal 532 and the negativeelectrode terminal 572 of the semiconductor module 500. Since theterminals of the semiconductor module and the capacitor module aredirectly coupled, parasitic inductance becomes low and uniform so thateach semiconductor module operates uniformly and stably.

It is also important to make the electrical characteristics of theplurality of upper and lower arm series circuits constituting the U-,V-, and W-phases as equal as possible. For example, it is important tomake the electrical characteristics of the direct circuits 50U1 and 50U2constituting the U-phase circuits the same as much as possible.According to the present embodiment, the capacitor module is fixed toface in the same direction with respect to the arrangement of the DCterminals 572 and 532 with the semiconductor module 500 forming thedirect circuit 50U1 and the semiconductor module 500 forming the directcircuit 50U2, and the physical relation between the terminals of thesemiconductor module forming the direct circuit 50U1 and the terminalsof the capacitor module that are connected thereto is the same as therelation between the terminals of the semiconductor module forming thedirect circuit 50U2 and the terminals of the capacitor module that areconnected thereto. It is thus possible to make the electricalcharacteristics substantially equal between the direct current circuits50U1 and 50U2 that are parallelly connected by providing the capacitorterminals and disposing the capacitor module along the direction inwhich the DC terminals are aligned.

Although according to the present embodiment a structure in whichterminals of the semiconductor modules and terminals of the capacitormodule are directly connected is the most preferable structure, theseterminals need not always be directly connected. For example, inductancecan also be suppressed to quite a low level by connecting the terminalsvia a connection conductor having a shape in which a positive electrodeconductor and a negative electrode conductor face each other inproximity, such as a direct current bus bar.

Further, the group of terminals 552, 553, 556, and 557 for control ordetection are arranged so as to directly couple with the control board372 shown in FIG. 7. Accordingly, fluctuation components for each phasethat are caused by the wiring between the semiconductor modules 500 andthe control circuit and driver circuit inside the control board 372become smaller and uniform. Furthermore, even when adding anothersemiconductor module 500 for each phase for which two semiconductormodules 500 are parallelly connected to thereby parallelly connect threesemiconductor modules 500, it is sufficient to merely dispose the thirdsemiconductor module 500 to form a side by side arrangement in FIG. 13,and thus the structure has excellent applicability with respect toproviding additional semiconductor modules 500.

Another configuration example and cooling structure of the semiconductormodule relating to the present embodiment will now be describedreferring to FIG. 36 to FIG. 40. FIG. 36 is an oblique perspective viewthat shows another configuration example of the semiconductor modulerelating to the present embodiment. FIG. 37 is a sectional view thatshows the other configuration example of the semiconductor modulerelating to the present embodiment, which is a view seen from thedotted-line arrows that are shown in FIG. 36. FIG. 38 is an obliqueperspective view that illustrates the flow of cooling water in the otherconfiguration example of the semiconductor module relating to thepresent embodiment. FIG. 39 is a sectional view that illustrates theflow of cooling water in a case in which the other configuration exampleof the semiconductor module relating to the present embodiment is loadedin a water-cooled case. FIG. 40 is another sectional view showing theflow of cooling water of two upper and lower tiers when the otherconfiguration example of the semiconductor module relating to thepresent embodiment is loaded in the water-cooled case.

The structure of the heat radiating fins in the semiconductor module 500shown in FIG. 36 and FIG. 37 differs in comparison to the semiconductormodule 500 shown in FIG. 18. More specifically, thick center fins 570 ofa thickness d are provided in the center of the heat radiating fins (Aside) 522 and the heat radiating fins (B side) 562. The position of thecenter fins 570 separates the upper arm chip 52 and 56 and the lower armchips 62 and 66 into upper and lower, and by providing the center fins570 a function is performed that separates the water flow into two upperand lower tiers (as an example, the thickness d is approximately 1.5 to2 times the thickness of the other fins).

FIG. 38 schematically shows the flow of cooling water in the heatradiating fins of two semiconductor modules 500. A water flow 650 from achannel inlet portion 246 (see FIG. 39) only flows into a lower tierportion (lower half from the center fins 570) of the heat radiating fins(B side) 562 of the first semiconductor module to form a water flow 651.Next, it becomes an upward water flow 652 on the channel case rearsurface portion 234 to form a water flow 653 on an upper tier portion(upper half from the center fins 570) on the side of the same heatradiating fins (B side) 562. Subsequently, the direction of the waterflow at the channel case front portion 224 is changed to form a waterflow 654 on the upper tier portion of the heat radiating fins (A side)522. Thereafter, the flow becomes a downward flow 655 at the rearsurface portion 234 to form a water flow 656 of a lower tier portion ofthe same heat radiating fins (A side) 522, and then the direction of thewater flow 57 is changed at the front portion 224 to perform cooling ofthe next semiconductor module 500.

As will be understood from the structure illustrated in FIG. 39 and FIG.40, the reason the water flow 651 is only formed on the lower tierportion of the heat radiating fins (B side) of the semiconductor moduleat the channel inlet portion 246 and does not flow into the upper tierportion is because a guide portion 660 is provided in an extendedcondition in the inlet portion 246 of the channel case front portion224. Further, isolation of the water flows flowing through the lowertier portion and the upper tier portion is achieved because of thetightness between the thickness d of the center fins 570 and, the wallsurface of the main unit 214 or the partition wall 271 (see FIG. 17).

The cooling effect achieved in a case in which the other configurationexample of the semiconductor module 500 that is shown in FIG. 36 isloaded into the channel case shown in FIG. 39 and FIG. 40 to constitutea power conversion apparatus is described below. The cooling effect willbe described in comparison with the flow path of cooling water in thechannel case shown in FIG. 14 (flow path formed in correspondence withthe total height of the heat radiating fins of the semiconductormodule). As shown in FIG. 38, the flow path sectional area issubstantially halved by causing the cooling water to flow separately onthe upper tier portion and the lower tier portion of the heat radiatingfins. Assuming that the inflow amount of cooling water that flows intothe inlet portion 246 of the channel case 212 is constant (because ofthe large capacity of the inflow source of the cooling water), the flowrate of the cooling water that passes through the upper tier portion orlower tier portion of the heat radiating fins substantially doubles.When the flow rate quickens, the amount of heat absorbed from the heatradiating fins by the cooling water also increases in correspondence tothe flow rate (the amount of heat absorbed by the cooling waterincreases almost proportionally to the side of the flow rate in acertain flow rate range). More specifically, by employing asemiconductor module having the center fins 570 shown in FIG. 36 andforming a flow path of cooling water by temporally separating the uppertier portion and the lower tier portion, the semiconductor modulecooling effect increases substantially.

Since the channel case is separated into the main unit 214, the frontportion 224, and the rear surface portion 234 as described in FIG. 39,production can be carried out using a die casting manufacturing processand thus productivity increases.

FIG. 42 is another embodiment of the structure shown in FIG. 5, in whichthe control board 370 shown in FIG. 5 is disposed at the bottom of thechannel case. In FIG. 5, the control board 370 having the controlcircuit 72 is disposed under the cover 132 and a signal is sent from theconnector 371 through the signal wire 76 to the control board 372 havingthe driver circuit 74. The control board 370 is cooled in the uppercase.

In FIG. 42, the control board 370 having the control circuit 72 isdisposed on the bottom of the channel case 214. By fixing the controlboard 370 to the bottom of the channel case, the arrangement cools thecontrol board 370 while also utilizing the bottom space, and achieves asize reduction effect in addition to enhancing the cooling effect.Further, by disposing the control board 370 that is susceptible to noisesince it has the control circuit 72, on the bottom of the channel case214, a structure with high reliability with respect to noise also can beprovided by disposing the terminals of the semiconductor modules 500 onone side of the channel case 214 and disposing the control board 370 onthe other side thereof to sandwich the channel case 214 therebetween.

1. A power conversion apparatus, comprising: a channel case having acooling channel built therein; and a semiconductor module having builttherein an upper and lower arm series circuit of an inverter circuit,wherein the semiconductor module comprises: a first heat radiatingmember made of a metal; a second heat radiating member made of a metaland facing the first heat radiating member; a case part that connectsthe first heat radiating member and the second heat radiating member; anupper and lower arm series circuit body disposed in a space between thefirst heat radiating member and the second heat radiating member; afirst insulating member disposed between the series circuit and thefirst heat radiating member; and a second insulating member disposedbetween the series circuit body and the second heat radiating member,wherein the series circuit body comprises: a plurality of powersemiconductor devices forming the upper and lower arm series circuit; afirst conductor plate that faces and is electrically connected with amain electrode of at least one of the power semiconductor devices; asecond semiconductor plate that faces and is electrically connected witha main electrode of at least another one of the power semiconductordevices; a positive electrode-side terminal connected with the firstconductor plate; and a negative electrode-side terminal connected withthe second conductor plate, an opening that links the space between thefirst heat radiating member and the second heat radiating member withthe outside channel case is formed in the case part and the case part isaffixed to the channel case, thereby placing the first heat radiatingmember and the second heat radiating member in the cooling channel, andthe positive electrode-side terminal and the negative electrode-sideterminal protrude in the same direction while being disposed outside ofthe case part through the opening in the case part.
 2. The powerconversion apparatus according to claim 1, wherein the positiveelectrode-side terminal and the negative electrode-side terminal of thesemiconductor module are so disposed as to face each other, and analternating current terminal of the semiconductor module is disposed ata position that is offset relative to the positive electrode-sideterminal and the negative electrode-side terminal in a directionparallel to a flow of cooling water.
 3. The power conversion apparatusaccording to claim 2, wherein the semiconductor module is held by thechannel case by being inserted into the cooling channel in a directionperpendicular to an axis that is parallel to the flow of the coolingwater, and at least one power semiconductor device for the upper arm andat least one power semiconductor device for the lower arm are sodisposed as to be offset in the insertion direction.
 4. The powerconversion apparatus according to claim 1, further comprising acapacitor module, wherein terminals are provided on the capacitor modulein such a manner as to face the surface of the semiconductor module onthe side of the positive electrode-side terminal and negativeelectrode-side terminal, the capacitor module is affixed to the channelcase, and the terminals of the capacitor module are electricallyconnected with the positive and negative electrode-side terminals of thesemiconductor module, where the positional relationship between thecapacitor module and the channel case is such that the positiveelectrode-side terminal, the negative electrode-side terminal and analternating current terminal of the semiconductor module are disposed insuch a manner that the positive electrode-side terminal and the negativeelectrode-side terminal of the semiconductor module to be connected withthe terminals of the capacitor module are positioned between theterminals of the capacitor module and the alternating current terminalof the semiconductor module.
 5. The power conversion apparatus accordingto claim 4, wherein the terminals of the capacitor module arerespectively provided in correspondence to the positive electrode-sideterminal and the negative electrode-side terminal of the semiconductormodule, and the terminals of the semiconductor module are respectivelyconnected with the corresponding terminals of the capacitor module.